An inventory is the space occupied by all items that your character or a non-player character has picked up are stored.
Fallout, Fallout 2 and Fallout Tactics[]
The inventory can be accessed by pushing the "i" key during the game. In the inventory you can change the armor you wear, use food and drugs, load/unload weapons you have, and change your two active weapons.
During the battle access to inventory costs 4 action points, but can be reduced by perk Quick Pockets. In Fallout Tactics, access to the inventory is free, but various actions in the inventory cost you action points and the vehicles also have inventories.
Fallout 3 and Fallout: New Vegas[]
The inventory can be accessed by pushing the default button to bring up the Pip-Boy 3000 ("tab" for PC during the game, B on Xbox 360 and O on PlayStation 3). Accessing the inventory is free during a fight and will freeze the game until you close the inventory.
The items are sorted into five base categories: weapons, armor, aid, miscellany, and ammunition. In the inventory you can change your weapon in hand, the armor you wear and use food and drugs. In Fallout: New Vegas, you can also put a weapon mod in a weapon and change ammunition of your weapon in hand.
Fallout: Brotherhood of Steel[]
The inventory can be accessed by pushing the "select" button for PS2 during the game. Access to the inventory is free during a fight and will freeze the game until you close the inventory.
The items are sorted into weapons, armor, and items. In the inventory you can change your three active weapons, the armor you wear and use drugs.