Final Fantasy XIII/Items

While there are many items in the game, unlike other Final Fantasy games you can only use a very small portion of those. In the Items section of the menu, you can see your weapons, accessories and components, but these are all used within the menu system, not during gameplay. Likewise, key items are found in the menu, and these aren't used in gameplay either, but represent special items your characters have or story-related items and access to shops. The list of items you can actually use is quite short and consists of consumable items you use in battle and shrouds that are used just before going into battle.

Most items can be found in item spheres or are dropped by enemies, but to get them in bulk you'll need to buy them from Unicorn Mart or Eden Pharmaceuticals. A few items aren't for sale however, so if you don't want to wait for chance drops you'll need to dismantle an upgraded accessory to get them.

Consumables
While in battle, go down to the Item option in the battle menu to see the available items for use. These items have one-time effects, such as healing your party or removing status effects. In general, the most useful (and therefore expensive) items are Librascopes and Phoenix Downs, although early in the game Potions may help as well. To remove status effects, it's usually better to rely on a Medic or Synergist. If you are aware of the status ailments enemies in the area inflict, you can also equip appropriate accessories to guard against them.

Elixirs are fantastic items, but, besides finding one in an item sphere, you can only get them by dismantling an upgraded Doctor's Code accessory. Except for the Librascope (bought at Eden Pharmaceuticals) and the Elixir, these items can all be purchased at Unicorn Mart.

Shrouds
Shrouds can be activated while in the field before engaging in battle, by pressing and selecting the shroud to use. Once activated, the effects of the shroud will last for 30 seconds. These can be used before cutscene battles as well. Shrouds are relatively rare, so it's best to save them for harder battles. Deceptisols are likely the most valuable shroud of all, as they let you sneak by enemies or, more importantly, get preemptive strikes on them, increasing the chance of getting a five star battle rating.

Except for the Ethersol, which can be acquired by dismantling an upgraded Energy Sash accessory, all shrouds can be purchased at Eden Pharmaceuticals.

Key items
As you make your way through the game, you'll find key items that are either possessions of the characters, used for in-game systems or other story-related items. Most of these items cannot be missed, as they are part of the main storyline and are given to you at different points in the game.