Kit

A kit or backpack' is the in-game representation of a player's class, and is used to carry that player's weapons and devices. An icon (and occasionally the kit's design) helps players identify the kit's class from afar.

Upon being killed, the player drops their kit (after a short delay in some games), which can be picked up by another player and swapped for his own.

Using another player's kit provides immediate access to the player's selected weapons and gadgets. Any deployed devices will still function for the original owner, though the player can resupply and deploy replacements (destroying the originals in the process).

Kit swapping can be crucial to keeping a Medic alive, as his own Defibrillator can be used to revive him if downed. The Swap Revive tactic is sometimes used to give each player their own kit back.

Dropped kits disappear after about 15 seconds, also removing most devices deployed from the kit. Notable exceptions include the Squad Leader Spawn Beacon from Battlefield 2142.

Trivia

 * In limited situations, kits can be used to disguise as the other team.
 * Swapping kits can also be used to keep a larger number of devices deployed in the field. This can be helpful in area denial situations, especially if the devices are too far away to redeploy safely. The kits must be swapped regularly to keep things from disappearing.