StarCraft/General strategies

Cloning
Cloning is a technique for issuing multiple different commands to a large group of units as quickly as possible. The most common example of this is sending your first four workers to mine. With a little bit of practice it is possible to send all four workers to four separate mineral patches at the same time. This is done because only one worker can mine one mineral patch at a time. Ultimately this makes a very small difference, and is not really necessary even at high levels of play, but depending on playstyle small things can make enough difference. This skill is also (perhaps more) useful for issuing multiple commands similarly to a group of units with spells or special abilities, such as Science Vessels or High Templar. This is more difficult, but potentially more rewarding.

Cloning How-To
Once again, the most common situation where players clone units is with workers. To clone your first four workers to four separate mineral patches, select them all, and right click on a mineral patch (tell them to mine) close to your base. Then hold shift, and click on the unit portrait of one of your four workers down in the bottom middle of the screen. This de-selects one of your workers; that worker will mine the mineral patch you previously selected and will not be given any more commands. You now have three workers selected; right click on another mineral patch near your base, and the three workers you still have selected will head there. Shift-click one more of your workers; now you have two, and the third one will keep mining that patch. Right click another patch, shift-click one more worker and finally you have only one selected. Right click on a fourth mineral patch, and now all four of your workers are mining separate patches.

While simple in theory, doing this fast enough for it to actually work will take a little practice, and it nets a very small gain. This need not be the first thing you learn, although its not a bad idea to try to do it every game since you have to send your workers to mine anyway.

The idea for cloning spellcasters is exactly the same. Select several units (they must be the same, or there must be units with the same abilities and the other units selected must not have any abilities) and tell them all to use an ability on a target. Shift-click one, tell them to use that ability (or another ability if you are fast and the units have multiple abilities) on another target. Shift-click and repeat until your last unit. Alternately, if you only want some of the units to use the ability, once you have issued as many commands as you want, tell the remaining units you have selected to move somewhere (by simply right clicking, even on the spot) to cancel the commands you previously issued while cloning.

You can also clone units to attack different targets. The best unit to do this with is the Scourge. The biggest problem with these suicide bombers is that they almost always overdetonate on targets. For example, 1 (non-upgraded) Scourge does 110 damage. A Terran Wraith has 120 HP; therefore, two Scourge can take it out. But in reality, this doesn't work. Let's say you have a group of 6 Scourge hotkeyed for emergencies, and two Wraiths start attacking your base. You right-click on a Wraith, thinking that once that one is history, the remainder will attack the other one; but in some cases, four or five Scourge will run into the targeted Wraith before it explodes, leaving only one or none to do minimal damage to the other one. This happens because units attacked by Scourge take a while to die. So here's what you do: first, move the Scourge a good distance away from the Wraiths so you can have some time. Now, right-click on a Wraith, and quickly deselect two Scourge by holding down the shift key and clicking on them. With the four Scourge you now have selected, right-click on the other Wraith. Quickly deselect two more, then right-click on some other spot away from the Wraiths. The six Scourge will make a run toward the targets and split up into pairs--one pair running into the first Wraith, another pair running into the second Wraith, and the last pair alive and well for the next crisis. The Scourge cloning technique works best with weaker air units like Mutalisks and Wraiths, because there's less units you have to deselect. Also, consider just using one Scourge each on these units. They'll have 10 HP left over after a hit, and just about any other unit will finish it off easily.

Basic Zerg Strategy
The Zerg have some pretty awesome stuff going for them. To begin with, the Zerg have the unique ability to produce every unit from only one building! This, combined with the fact that the Zerg's units are relatively cheap to produce, allows for masses of units to be quickly built. Therein lies the Zerg's true power, their units aren't very powerful, but they have a lot of them. Another interesting asset of the zerg is that all their units (including buildings) heal over time, regenerating health automatically.

Zerg have what is possibly the most restrictive building requirement in the game; nearly all buildings must be built on creep. The only buildings that don't require that they be built on the "creep" are the Hatchery and the Extractor. The creep is an expanding carpet that grows slowly from Hatcheries. It can only be expanded by building more hatcheries or Creep Colonies. An important thing to remember is that any Zerg player may build upon any Creep. It doesn't have to be "your" creep. Indeed, players don't own the creep at all. Creep also recedes when the hatchery or creep colony that produces it is destroyed. Terran and Protoss players cannot build on creep.
 * The Creep

Upgrades are essential for the Zerg. Because the Zerg can produce so many units upgrading their attack and defense is very rewarding. Zerglings fully upgraded with Metabolic Boost, Adrenal Gland and Melee and Carapace upgrades can devastate an enemy's base before they know they are under attack. Burrowing is an extremely useful ability as it allows any ground unit aside from the Ultralisk and broodling to hide from enemy units. It also makes Zerg very effective at scouting as a burrowed unit can remain unobserved anywhere -unless a detector is nearby or a Terran player does a Scanner Sweep of the area- while still able to see all around.
 * Upgrades

Strategies
Send your Drones to mine minerals immediately. Start Morphing one of your Larva into another Drone. Quickly send your Overlord to explore. Continue to mine and construct more Drones as soon as you have enough minerals. Once you have 6 Drones mining stop producing Drones. Continue to amass minerals until you have 200. The moment your minerals reach 200 produce a Spawning Pool. Build one more Drone while the Spawning Pool completes its morph and send it to mine. When your Spawning Pool completes you should have 3 Larva and at least 150 minerals. Use this to quickly produce six zerglings (two Zerglings hatch from each Egg). As soon as you have your Zerglings, attack your opponent with them. If you haven't already found your opponent with the Overlord the 'lings should find the base quickly. Note that the Six Pool Rush is most effective on smaller maps with few players. If executed properly you can usually cripple if not outright kill your opponent. If the attack fails, however, your minutes are numbered as you will not have enough time to recover before your opponent finds and kills you. Weigh the ups and the downs of the Six Pool Rush carefully.
 * Six Pool Rush

This is essentially the same thing as the Six Pool Rush except that you build no Drones. Simply set your drones to mining and when you reach 200 morph one of them into a spawning pool. Don't build any more drones! When the pool completes you should either have 150 minerals or be extremely close to that total. Again, turn the three Larva into six Zerglings and rush their base. This is even faster then the Six Pool Rush but should not be attempted unless the map is very small.
 * Four Pool Rush

In most maps (and especially in "money maps") it is wise to have many Hatcheries so as to produce even more units even faster. If you have enough minerals also build extra Hatcheries at your expansions, this will allow you to rebuild quickly if your enemy finds a base.
 * Multiple Hatcheries

Nydus Canals are buildings that allow ground units to move instantly from one end to another. After constructing the first end of a Nydus Canal you may place the other end on any creep that you can see. This allows you to move quickly from one base to the next so as to defend against attacks. Personally I've found the Nydus Canal to be instrumental in several instances where a Zerg opponent has guarded only the entrance to their base. Either infest a unit with Parasite (a Queen ability) or send a pack of Overlords or Scourge to your opponents base so that you can see their creep. Make sure that you have plenty of ground units and a Nydus Canal without an exit placed before you do this. Once you can see the area you are going to build on quickly place the exit of your Nydus Canal. Send all your units through the Canal and destroy as much of their base as possible before they notice you.
 * Nydus Canal

Basic Terran Strategies
Like the name, mass siege tanks and place them all near your enemy's base and put them in siege mode. The ones in front should fire at the base, and when more things go "boom", send the ones in the rear to the front and put them in siege mode and they should start laying waste. Continue until everything is destroyed. Keep a few Goliaths on hand in case of an air counter-attack
 * Tank Push

This tactic is useful against the Protoss Zealots early in the game, but is extremely effective against the Zerg. Create the requisites for a Firebat quickly (Barracks, Refinery, Academy) and have at least 2 Barracks. Mass produce Firebats until you have 12 - 18 and rush the enemy base. This provides a viable alternative to other rushes in that the Firebats, with their 16 firepower, can also defend your base in the case that you get rushed. With their high firepower, cost-effectiveness, and spread damage, Firebats can easily devastate an enemy base.
 * Firebat Rush

There are a few fundamental principles that every beginning StarCraft player needs to know. Amazingly, they are very similar to that seen on a more complicated level in all the wars ever fought. It is this similarity that enables StarCraft to closely resemble military warfare and to provide attraction for millions of children and teenagers, even professional players, sixteen years after Starcraft's debut.

Geography: Where in the World is...?
Geography plays a critical role in determining the outcome of particular tactics, strategies, battles, and thus matches. Players must know their surroundings, the surroundings of the enemy, and everything else as well (see Scouting below) in order to manipulate the map to their advantage. For example, islands and lands cut off from surroundings require drops and air superiority, something not quite as necessary in a landlocked realm. Higher ground even more so; and shortcuts or back alleys can cripple the opponent by bypassing defenses to bring forces to where they are unexpected. Therefore, geography becomes particularly important in deciding where to place units, where to build structures, and what to expect from the opponents.

Scouting: Know Your Enemy and Yourself
Scouting is an inherent part of the game, and essential for any sort of progress in skill. Knowledge of your enemy's actions is vital to making good and effective decisions throughout the game. Often, when asking a more experienced player how they should improve, the answer is 'scout more' or 'scout better'. However, what does this mean exactly?

Just blindly sending your units out to random positions on the map serves little purpose. So here are a few pointers on when and how to scout, and most importantly, why it's important in the first place.

Purpose
At the beginning of the game, you know nothing about your enemy. After your initial scout finds the enemy, try to stay in his base for as long as possible to try to find out what his build order is. Send scouts periodically during the beginning phase of the game so you know what you are up against.
 * Build Order

A very simple example is Zerg versus Protoss. With your initial scout (either drone or overlord), if you see a double-gateway build, you know he is rushing or building up an early attack force. Whereas if you see single gateway to cybernetics core, you can deduce that he is teching. Without this information, you would be playing blind and trying to guess at his plans.

The good thing about build orders is that once you reach a certain (low-moderately skilled) level of play, it is not difficult to figure out what your enemy is doing, as faking a build order to provide you with false information is usually not worth the effort.

Later on, scouting an opponent's base for tech buildings allows you to prepare in advance for your opponent's units. For example, if you spot a Greater Spire, you can expect either Guardians or Devourers to make an appearance.

The location of your opponent's army is very important. Armies are generally mobile, and in the later stages of the game it becomes increasingly difficult to defend all of your expansions well. Thus, knowing the location of your opponent's army will allow you to place your forces accordingly - either defensively, against his attack, or offensively, striking a hole in his defenses.
 * Army Position and Composition

In addition to location, the composition of the army is also important. Once a player gains enough knowledge of the game mechanics, knowing the effective counters to various units becomes natural, and the player can prepare in advance for what he knows his enemy has.

Possibly one of the most important functions of scouting is to discover your opponent's expansions (or desire to expand) early, and thus enable you to stop them. An expansion is most vulnerable when it is in the process of being built, or just being built. Once an expo is established, it is significantly easier for the defending player to defend it. In higher level games, this type of scouting occurs frequently, as an extra expansion is often enough to tip the balance for the player to win the game.
 * Scouting Expansions

Timing
This is a very difficult question to answer. The simple answer would be 'all the time', but of course its impractical and inefficient to follow this doctrine. A more accurate but equally useless answer is 'you will eventually feel when it is the right time to scout'. At a certain level of skill, you will gain a gut feeling that tells you when and where to scout. Things that your brain pieces together behind the scenes while you are busy making decisions, will be evaluated by your brain and then bubble up as a thought. "He has a small army, and he isn't teching hard. He must be expanding. Go scout it out", "His army at his main base is too small, he must be setting up an attack", are examples of how you can evaluate the present circumstances in the game to come to conclusions on your enemy's actions BEFORE sending out a scout. This is learned through experience and observation.

Before you gain this sense though, there are several key points in the game when you should scout.


 * 1) At the beginning. Discover your enemy's location and his build order.
 * 2) When you finish your first tech (Tanks, Lurkers, High templar/Reaver/Corsair). Your opponent's tech choice will be coming into play at around this time as well.
 * 3) Whenever you are not in a major battle, after the first big battle of the game. Search for new expansions.

These are just guidelines that will help put some structure in the 'scout all the time' doctrine.

Methods
Terrans hold the single most powerful scouting tool in the game. The Comsat add-on to the Command Center. Comsat provides instant vision of a large radius at one position of the map for several seconds, revealing units and buildings, as well as cloaked or burrowed units. At a high level of play, comsat is vital to keeping track of the enemy across the map.
 * Terran

Hotkey your Comsat (8, 9 and 0 are common) to allow for quick access. Also build multiple comsats once you expand, as they are invaluable.

Aside from Comsat, Terran have a few choices.

SCVs are often useful scouts, as they are cheap, expendable (you often have 'extra' SCVs), and are available throughout the game. Their ability to 'walk through' units while targeting a mineral patch can also be a useful ability.

Vultures are fast and also relatively cheap. However their mines are great for scouting, as they hamper the movement of enemy troops, and are 'invisible' to most units. Place mines close to mineral lines, near where an expansion command center would be placed (or right under it, to block the enemy from building immediately on the spot), and you have instant notification if the enemy is expanding there.

Wraiths and Science vessels can also be used as scouts later in the game, as they are flying units.

One more method of scouting: Early in the game, before you build your first Comsat, it can be difficult to find out what your opponent is doing. Your marines are slow and easily outnumbered, so it is difficult to scout with them. One option is to build an Ebay outside of your opponent's base (out of sight, of course), and lift off and float it over your opponent to see what he is building. This is usually not necessary, but it remains as an option for you.

Overlords are the best scouts in the game. They are cheap, detect cloaked or burrowed units, have high HP, can fly, are relatively fast (with speed upgrade), and a Zerg player always has many of them. In the beginning of the game, scout out your opponent's base with your starting overlord and the first overlord that you build (or alternatively, your starting overlord and a drone). Have your overlord hover over your enemy's base until he starts producing anti-air units (marines, dragoons or hydralisks). The ability to effortlessly discover your opponent's build order is priceless, so always take advantage of it.
 * Zerg

Later in the game, research the speed upgrade. This will make your overlords invaluable as scouts, as they can watch over every expansion (and run away without dying if they are discovered). Patrol them along places where you believe your enemy will send his army. Unlike the other races, with overlords, a Zerg player CAN always be scouting.

Zerglings serve as great scouts very early in the game due to their cheap cost and speed. Building zerglings and spreading them all over the map early in a game will reveal most enemies and some expansion zones. Their ability to burrow makes them very good scouts in theory, however the effort needed to research burrow and hide your zerglings is often not worth it.

Of all the units in the game, the Protoss Observer is probably the best scout of them all (see the pattern?). Inexpensive, flying and cloaked, observers allow unparalleled 'observation' of the battlefield.
 * Protoss

Use them to infiltrate your opponent's base and keep an eye on his tech and what he is building. Use them to keep track of possible expansions, army movements, and everything else. The only downfall of observers is you often don't have enough of them to scout what you'd like.

Corsairs are the protoss' second most useful scout, however due to the nature of the game, they are usually only viable on island maps or versus Zerg. Once you build your first corsair (assuming a corsair-first build against zerg), send it directly to the zerg's base to discover his tech and harass his overlords as well.

More commonly used is the Zealot, because it is readily available, has high hp, and with speed upgrade is one of the faster land units in the game. After speed upgrade, because they are so much faster and later in the game less of a money issue, they are commonly used instead of probes to scout expansions and run deep into bases.

Early in the game, probes are useful scouts for the same reason the SCVs are (and probes are slightly easier to control too).

The Base: The Heart of it All
Players have many ways of constructing structures. The fastest method is to use the hotkeys B for Basic Build and V for Advanced Build, then pressing the associated hotkey for a particular structure while hovering the mouse near the prospected building site.

Buildings take a rather short time to build, and are rather cheap compared to units. Therefore players generally build ample buildings. Another reason of doing this is use as backup. If an enemy destroys a Protoss Gateway, for example, the player cannot build Gateway associated units nor travel up the tech tree for about another crucial minute (until a Gateway is rebuilt) UNLESS the player has at least one that was not destroyed.

Building locations are also crucial, as they may determine the ease or difficulty of bypassing units-either moving your units from one front to another or to prevent enemies from simply running past defensive structures. Buildings can be used to protect a Terran Siege Tank in Siege Mode as well as grant it extra range; enemies attacking it would be outside the 'too close' range. Meanwhile, the same buildings could block a Reaver's attack pathway or at least slow down its rate of fire.

Defensive structures should be placed at chokepoints for maximum effectiveness and should be spread out throughout the base-especially at resource nodes-to defend against enemy infiltrations and provide response time for your units.

The Terrans have the least need for defensive structures, because generally a defense will include units such as a Siege Tank that cannot be defended with a Bunker. But, combined with a supply depot, a bunker and two or so siege tanks, added with missile turrent at the choke point, this is an almost impreganeble position, given the SCVs are there to help repair the tanks, bunkers and supply depots. By the time an enemy has destroyed everything outside the Bunkers, the paltry resistance of Marines and Firebats will not save a base or expansion.
 * Defensive Structures

Zerg players turn almost all creep colonies into their derivatives, because doing so only costs an additional 50 Minerals (a total of 125), compared to the 100 for a Terran Bunker or 150 for a Protoss Photon Cannon.

The Tech Tree related structures of each race, if seen by an opponent, will reveal to the opponent all of a player's buildable units, which reduces the element of surprise and allows the enemy to concentrate on units that are effective against the player's own units rather than spreading out their military variety to cover every contingency.
 * Main Structures

For example, a Terran Machine Shop will alert any enemy to the production of Terran Siege Tanks and will result in their constructing units such as Zerg Queens, Protoss Archons, and any type of aerial units, all of which are effective against the Siege Tank for their own reasons. Then if the player were to invest in Siege Tanks, the enemy will be prepared. However, if the player instead chooses to build anti-air units or the Terran Science Vessel with Irradiate, which are effective against the Queens, Archons, and air units, then the advantage will return to that player.

Oftentimes opponents will attempt to destroy lone key structures, such as Gateways, Cybernetics Cores, Factories, Starports, Spawning Pools, Spires, and Ultralisk Caverns in an attempt to cripple a player's ability to produce a certain type of unit or advance to the next step of the Tech Tree. Since a player's base is often well-defended, destroying such a structure rather than attacking units will bring a significant cost on an enemy's resources. Therefore, players may trick them into an attack with a lone obvious target, then produce a second one hidden deep inside a secure base. Then if the enemy attacks, the player will still have the backup, and the enemy attack will be wasted. Note that Zerg players are most significantly affected by the loss of a Tech unit, since they often have only one of a Spawning Pool, Hydralisk Den, Spire, Queens Nest, Ultralisk Cavern, and Defiler Mound.
 * Backups

Terran
By Flying Cover we mean the use of a large floating structure to defend a smaller ground unit (usually a Barracks or Engineering bay is used because they are mainly used to teching). Because of the gameplay, player opponents cannot target any unit completely hidden beneath another unit. With the Terrans' flying structures, this can become a significant benefit in the defense of a base because unless an enemy uses splash damage attacks or spells such as Psionic Storm, they cannot target the covered unit until the Flying Cover is destroyed. Destroying a Flying Cover Barracks with 1000 hp is much much harder than destroying a Battlecruiser with 500 hp.

The obvious counter to Flying Cover is to Stop all units and have them automatically attack the Covered unit. However, doing so is not effective because the units may not attack that particular target, and almost never will if the Covered unit is a spellcaster such as a Terran Ghost.

Flying Cover with floating Terran structures is most effective when the Barracks or Factory is directly adjacent to the defending military and the military is slightly above the structure. That way, as the battle opens up, the structure floats up and immediately blocks the view of the Covered units.

The same strategy can be used to covers a player's buildings thus disallowing the opponent to see how they are teching or what they are planning. For example, in one game, SlayerS_'BoXeR', a great terran player, floated his Engineering Bay over where his Comsat Station add-on would go, and instead he built a Nuclear Silo in complete secrecy. He later launched the nuke successfully at an unsuspecting Terr@n-[Nes] and won.

Zerg
The Zerg is the only race that cannot build defensive structures at expansion points before beginning the construction of a Hatchery at that location. Therefore, players must defend their hopeful expansion points with an adequate supply of troops.

Creep can be a very limiting factor, but constantly trying to expand it will economically ruin a Zerg player, primarily because the creep does not DO anything. Instead of building a tangle of Creep Colonies, players should concentrate on growing Hatcheries, forming hatchery clusters at their main base. The advantage of doing so is that players have ample unit-constructing facilities for when their expansions finally begin to turn a profit.

Rushing: Shock and Awe
Rushing is generally considered a low-level strategy, primarily because advanced players are often prepared to resist a rush and because rushing causes the player to fall behind on their economy at the beginning of the game, which would ultimately result in an enemy victory if the rush is not successful.

Rushing does not have to be totally successful--taking out an enemy base completely--to be rewarding. If a handful of rushing units can dispatch multiple enemy workers, then the enemy economy will suddenly be in an even worse condition than that of the rushing player. The most efficient way to dispatch as many workers as possible is to order a regular move to a spot near the worker line, then hold shift (used to queue orders) and order an attack response in a random spot in the middle of the worker line. This way, even if your opponent has built a decent defense, your units will run past the base defenses and immediately start attacking the workers, with little requirement for micromanagement.
 * Performing Rushes

In order to succeed, however, rushes must be conducted swiftly, either by quickly obtaining a handful of low-level units at the expense of economy and technology, or by quickly obtaining a handful of high-level units at the expense of both economy and all other military.

In order to properly resist an enemy rush, it is best to have either one defensive structure protecting the base and mining operations or a handful of units to repulse an enemy attack. The former is cheaper, because defenses are inherently cheaper than normal units, but is also inflexible, especially when the enemy scouts can report what structures a player is building and the enemy can thus choose to expand instead of obtaining military units. In other words, the enemy would be forced to obtain units for each of your units, while the enemy would likely create one expansion for about every three defensive structures, because the enemy would never fear an attack by your static defense (they DON'T MOVE).
 * Resisting Rushes

Defense: Harder than a Rock
Starting with the rushing strategies, players constantly attack enemy bases throughout the rest of the game, ideally without any break in the battle. Defenses are very critical, and static defense is cheap, but players must also try using units for defenses because players can only win with units, and not with static defenses (they DON'T MOVE). There are many different strategies, all of which depend on the unique attributes of each unit.

Surprisingly, defenses are some of most fragile buildings of all species. Therefore, a strategy called "walling in" is often used. The basics of walling in is to build a different building stopping melee units from attacking the defenses, or requiring them to run around the building. Terrans generally have the best walling because they can repair their structures while they are lifted off (so before they die, lift them, then defeat the threat, then repair when possible).
 * Walling In
 * In a Protoss vs. Terran game, the terran will probably use a walled in missile turret for Dark Templar detection that the Templar can't reach.

Terran
This building should have some protection from ground attack, either tanks or bunkers work well. Because of their very cheap cost and ability to protect units from from air attacks, the turret is good at protecting the assault unit in the front-lines too.
 * Turret

Siege Tanks can be extremely effective in augmenting your defense. In Siege Mode, they deal 70 points of splash damage (more if upgraded), and when placed around your base perimeter are very effective at stopping whole waves of enemies. Siege Tanks are essentially stationary defenses that can be repositioned if necessary. The best way to use Siege Tanks for defense is to place them on high ground near the entrances to your base. A group of 4 to 6 Siege Tanks can stop whole armies in this way. Be sure not to use Siege Tanks exclusively for defense, as they have no attack against air units, meaning a Siege Tank-only defense is screwed if they build even a small number of air units.
 * Siege Tank

Zerg
The Zerg have two different types of defensive structures that drones can be morphed into. Each one is specialized, one for air and one for ground.

The sunken is a substantial weapon with 400 hit points and 40 attack, but with its complete vulnerability to air and slow recharge time, these are not meant to be the sole defenders of a base.
 * Sunken Colony

As mentioned in the sunken defense section, the Zerg use two types of defensive structures; one for air and one for ground. Spores alone, once detected, will be quickly done away with a drop or simple ground forces if not reinforced with guardians or maybe ultralisks. They are basically ineffective against any large air force even if massed and ready.
 * Spore Colony

Protoss
A common mistake among amateurs is to rely too heavily on Photon Cannons, placing too many of them close together in "cannon farms" or concentrating them in bottlenecks of anticipated attacks. The opponent can easily counter this by investing in air forces that can bypass the cannon farms, or by developing an antidote to the cannons such as Guardians. Either way, the heavy investment in stationary artillery is neutralized, and the enemy's superior investment in mobile units is likely to pay off.
 * Photon Cannons

Keeping several High Templar near the base often proves to be an invaluable component of defense, particularly in combination with Photon Cannons and Dragoons. Having High Templar that can get just within range of a bottleneck the enemy is trying to pass through, in a tightly packed crowd, can have brutal effects on attackers. Keeping a few High Templar wandering around the core and back areas of the base can provide effective aerial defense.
 * High Templar

A few Reavers buried deep behind the Zealots, Dragoons and Photon Cannons forming the front and secondary lines of your defenses can greatly augment their defensive power and can be very difficult for the enemy to effectively counter. Remember not to bury the Reavers too deep, since Scarabs have to circumvent every unit on the way to the target.
 * Reaver

Containment: Full Circle
Generally, this comes in the form of Protoss building photon cannons or gateways at an exit, or terran building bunkers or barracks. This strat is also known as "proxying", but it can contain the enemy well. For zerg, lings may be burrowed at a ramp.
 * Early Game

Terran probably does the best containing. It can place siege tanks around the base to prevent any means of expansion. Vulture Spider Mines also work, as they can destroy cloaked units. Missile turrets can be used to contain the enemy in an island map. Zerg can burrow lurkers around the base, providing a wall that does not require much management. Protoss has no units too capable of containing well.
 * Mid Game

Terran probably will stick with tanks and turrets, while protoss will use the carriers. The Interceptors will kill air and ground units, so a blockade of carriers is virtually impenetrable. Upgraded Goliaths have the same range, and the only anti-air weapon with greater range is the yamato gun.
 * Late Game


 * The Mid game and Late game containments only work if your opponents haven't expo-ed.
 * Any good containments lead to cornering and killing.

Terran
The Terran tech is quite simple in terms of build order, but looking deeper, there is room for movement.

The first building should be the barracks, allowing for the advanced tree and a different section for the basic tree. After Barracks, base your tech on your enemy's species. Either way, build an early refinery. Against Zerg, build academy, followed by immediate Stim research, U-238 and Medic energy upgrade. Later, restoration and optical flare are highly recommended. (for use against parasite, ensnare, and plague, and for blinding overlords for wraith use) Remember to build a comsat station, to spot lurkers and for scouting; terran has no reliable scout. This is the infantry tech.

Starports have two benefits: access to air units, and access to the science facility, needed for second level upgrades. Build a control tower, as only the wraith can be built without one, and wraiths are almost useless without cloak (which must be researched at a control tower).

Zerg
After the Spawning Pool, Zerg players have three options: make more Zerglings, create a Hydralisk Den, or mutate into a Lair. Creating more Zerglings is used to counter the use of Dragoons and Hydralisks. The Hydralisk Den is used to counter fast techs to air units, firebats, Zealots, and M&Ms via Lurkers. The Lair is to open up another available tech tree.

After the Lair, there are three more options: create a Spire, evolve Lurker Aspect, or create a Queen's Nest. The Spire is used for the production of Mutalisks, which are used to counter Zealots, Dragoons, Firebats, and Reavers. Lurkers are used to counter armies of M&Ms or zerglings, or massed low-hp units in general. The Queen's Nest enables the production of Queens, used with Spawn Broodling to counter Tanks, and also to tech to Hive.

After the Hive Tech, three more possibilities present themselves: Greater Spire, Ultralisk Cavern, and Defiler Mound. Greater Spire allows for production of Guardians, for mounting a final attack involving a steady crawl with Hydralisk or Mutalisk support, and the Devourer, used to counter flagships. The Ultralisk is used to mount a final attack a different way, by taking the hits of the enemy while Zerglings and Hydralisks in tow cause huge damage. The Defiler Mound allows for the research of Plague and Dark Swarm. Plague is used to counter flagships and to weaken enemy defenses, while Dark Swarm is used to cover Hydralisks defending from flagships and to cover Zerglings as they attack the enemy base.

Protoss
The Protoss's tech is based on one structure- the cybernetics core. The cybernetics core allows for the production of all the three advanced tech trees. Of course, the first building is a pylon, followed by a gateway, more pylons, more gateways, etc. The forge is optional, but highly recommended, because it is needed for the photon cannon. The forge is often built early, unlike an engineering bay for terran, required for the ground-to-air missile turret.

After a cybernetics core, the executor has a choice of three trees- templar, air, or robotics. The choice, of course depends on the strategy your opponent is using. If you don't know the strategy, build a robotics facility, followed by observatory and sight range. The templar tree has two uses- templar and speedlots. The templar would be used to counter zerglings (dts, archons, and storm), hydralisks (storm), or mutalisk (storm or archons) for zerg. The robotics tree has three units for three uses, shuttle, observer, and reaver. Shuttles are used for drops, such as the reaver drop. Reavers are used in drops, or for bypassing defenses. Observers are for cloak detection and spying. The stargate tree is for air units, like corsairs and carriers.