Age of Empires II: The Age of Kings/Villagers

Villagers
Villagers are the resource gathering and construction workers that are essential for building and maintaining your base. They are the meat of base/force/army. Without them you will eventually lose. They collect Food, Wood, and Gold.

Villagers cost 50 food to make and spawn at the town center

Sixshooter's suggestion of usage
Make six villagers into farmers usually around a protected area like the inside of a base. Send five villagers to mine for stone or gold, then create 10-15 (based on population limit of 75) and split them into two groups and set them to collect wood in two different areas. Create 1 or 2 villagers for base repair and additional construction. If attacks are heavy, change the number of static villagers to 3-5, but if you can avoid it, don't take villagers off of resource collection to make the extra numbers. I like to use my 1-2 villagers as construction units on advance bases (built for offensive purposes) that I build just outside a target base. When I do so, I protect them with 10 cavalry or 10 of certain special units.

If you gotta build a lot of buildings at once, or a wonder, either ignore this, or build an additional 5-7 villagers for normal high speed construction, but if you're building a wonder you want 10-12, this is one of the few times I'd suggest taking resource collectors to make your numbers, and only do so with wood or food. Gold and Stone are too rare to stop collecting when you find it.

Villager Techs
Loom: gives Villagers 15 hit points, +1 attack/+1 Pierce

Wheelbarrow: Villagers move 10% faster and carry 25% more resources

Gold Mining: Villagers mine Gold 15% faster

Stone Mining: Villagers mine Stone 15% faster

Double Bit Ax: Villagers chop wood 20% faster

Hand Cart: Villagers move 10% faster and carry 50% more resources

Bow Saw: Villagers chop 20% more wood

Gold Shaft Mining: Villagers mine 15% more gold

Treadmill crane: Villagers construct buildings 10% faster

Two Man Saw: Villagers cut wood 10% faster

Spies: Doesn't directly affect your villagers, however, the number of enemy villagers are taken into account when tabulating the cost of the tech

Victory by killing enemy villagers
Generally if you can kill the villagers you can kill or cripple your enemy in the battle. In Multiplayer on lower difficulties or even higher difficulties on occasion, sometimes the enemy will surrender if you manage to kill all his villagers, sometimes he'll even do it if he still has a town center.

Their are many various ways to winning AoE games, one such way is resource war, (getting more resources than your enemy so you win) and in this strategy killing the enemy villagers is a crucial part to achieving success. The AI tends (as do some players) to put their villagers to work outside the base collecting resources. They usually put more villagers into cutting wood than they do collecting stone and gold (though not always the case) and these villagers are a good target for your units.

There are generally three ways to approach this.

1. Take 10-15 projectile units (higher attack units the better) and place them at a lumber camp, put them on no attack status and just point and click at each villager, cav archers are better because the enemy usually sends units to stop you, and alot of the times those are knights and other mounted units.

2. Swarm in with melee mounted units and kill them off in a big rush, you want at least 15 because they all start running away.

3. Build a castle by an active lumber camp and just watch as the villagers die in mass at the foot of your castle. Be careful not to attack anything while doing this, or the AI will be alerted to your presence and try to shut you down. This also causes a swarm from the AI where they send units to destroy you're castle, so you want some additional units on stand by to protect it from siege weapons if they make a try.

Finally, to achieve your victory over a particular faction, especially in the single campaign mode, when you destroy the town center, you want to make sure you get all the villagers, because if you don't, they'll either build a new town center somewhere else, or build up the needed resources and build a town center. Remember, all it takes to restart a destroyed base is 100 wood to build a lumber camp and from there, one villager could in time completely rebuild a base if he has access to all necessary resources.

If you kill all villagers and they ability to make villagers, sometimes the AI will launch all it's ground units at you in attempt to rush you to death.