From Team Fortress Wiki
In Team Fortress 2 there are two companies locked in a war against each other, RED (Reliable Excavation Demolition) and BLU (Builder's League United). These two companies are the teams a user can play as. There is also a third "team", Spectator, which a player can be if they wish to spectate the participating players.
When the player joins a server, or presses whichever key is bound to
.); an interface pops up allowing the user to select their team: 1: Random/Auto Assign, 2: Spectator, 3: BLU or 4: RED.
By default, a player may be unable to choose a particular team if there is player difference (between the teams) of 1; the player will only be allowed to choose the smaller team. Server administrators are able to turn this feature off, or adjust the player-difference number via the Console command:
Once in-game, a player can check the teams by displaying the Scoreboard via the default key:
Tab, or the console command
Some classes have weapons that are designed to interact with a player's team, for example the Medic's Medi Gun is used to heal teammates and the Soldier's Buff Banner, once charged, makes all damage done by nearby teammates mini-crits.
A team can consist of any number of players, each being one of nine Classes. Each class is designed, and has weapons, to fulfil a particular role within a team, and all nine classes are split into 3 sub-groups: Offensive, Defensive and Support.
In spectate mode, a player can watch the match through the eyes of any of the participating players, or roam around freely. While respawning, a player will be in spectate mode (but will not be listed as part of the Spectate team) until that player respawns.
While spectating, a player may use the primary and secondary fire buttons (Default:
Mouse 1, and
Mouse 2) to cycle their view through the participating players; a player can also use the spacebar key to switch between a first and third person perspective, or go into "noclip" mode (fly freely around the map).
- A yellow and green team existed in some maps in the original Team Fortress.