4v4 is a format of Team Fortress 2 competitive play. It features a 4-on-4 scenario with a limit of one of each class, and is predominately played on various King of the Hill maps, though it uses some Control point maps as well. It is more fast paced and deathmatch-focused than standard 6v6 competitive play.
4v4 forces one of each class with the only exception being you cannot run Heavy and Medic at the same time. Beyond this any class composition is allowed. Because of this and its sparse weapon ban list, the number of strategies and team make ups that a 4v4 team can employ is immense.
The standard line up tends to be
The Medic is usually a constant, and is only switched for a Heavy when the situation is dire. The Demoman gets much more flexibility for offclasses than he does in 6s, but is still usually run full time. The Scout and Soldier, however, can switch class every life. Pyro and Sniper are very popular and can do a great deal of work when the enemy isn't expecting them.
4v4 is currently only run by UGC and as such only has one list of maps. The format used to be played by Ozfortress, but was discontinued. The current maps being played by UGC for 4v4 are:
Roughly two maps are swapped out every season, and some of the following maps (which have all been played in past seasons) may be rotated back in. Maps that have been previously used, but are not currently in the map pool include: