Each team has several factions that can be chosen as the player's third-person model. Excluding the VIP, there are four factions per team in Counter-Strike and Counter-Strike: Source, five factions per team in Counter-Strike: Condition Zero, and seven factions per team in Counter-Strike: Global Offensive. None of the factions have an effect on gameplay and the differences are purely cosmetic.
In Counter-Strike: Global Offensive as well as in the Counter-Strike (Xbox), players are no longer allowed to choose their factions. Instead, each map contains its own official CT and T factions (e.g. Vertigo's SWAT and Professionals).
Each faction in Counter-Strike: Global Offensive has five model variants that are randomly chosen upon spawn. The models have different details but are generally identical.
The hostages, despite being non-playable and are simply objectives, are often considered a faction due to their human nature (comparable to the C4, which is also an objective but is a piece of equipment).
Both Counter-Terrorists and Terrorists have their own unique equipment that cannot be bought by the opposing team (though some can be picked up). Examples include the Maverick M4A1 Carbine, which can be bought by Counter-Terrorists only, and the AK-47, which are exclusive to the Terrorists.
Teammates can speak to each other using radio commands (default = Z,X, and C) without the risk of the opposing team hearing them.
In assassination (as_) maps, the Counter-Terrorists have a single member on their team who is the VIP. The VIP has to rely heavily on his team because they cannot purchase any equipment, although they are given an USP with 24 bullets as well as 200 kevlar at the beginning of the game. The VIP will need to go to a specified location where he can escape, thus winning the round.
In bomb defusal (de_) maps, one Terrorist will spawn with a bomb, that will need to be planted at one of the bomb site (Bomb Site A/B). When Terrorists plant the bomb, the Counter Terrorists objective is to defuse it. It should be noted that when the bomb is planted the Counter-Terrorists need to defuse it even if they killed the whole Terrorist team.
In hostage rescue (cs_) maps, the Counter-Terrorists must rescue hostages while the Terrorists have to prevent them from doing so. The Counter-Terrorists must spot the hostages and escort them to the hostage rescue zone. The spot and rescue processes will give money. Any injury inflicted on the hostages or killing them will result in a penalty.
In escape (es_) maps, the Terrorists must traverse through a map to reach the Terrorist escape zone or eliminate the opposing team to win. Meanwhile, the Counter-Terrorists are required to neutralize the Terrorists or prevent them from reaching the escape zone until the time expires.
- Different factions also have different hand models in Counter-Strike: Global Offensive.
- Unlike previous games, Counter-Terrorists and Terrorists have different animations in third person. Terrorists always have their firearms on the hip (excluding sniper rifles) while Counter-Terrorists always aim all weapons on the shoulder (when standing still).
- In every Counter-Strike game, the AK-47 is always fired from the hip when used by the Terrorists (unless in a crouched position in CS 1.6 and CZ or used by NPCs in Deleted Scenes). When used by Counter-Terrorists, they will hold it in the same way as other assault rifles.
- In Counter-Strike 1.6 and Condition Zero, the IDF Defender is aimed from the hip when used by Terrorists. Meanwhile, it is fired from the shoulder in Counter-Strike: Source.
- All models in all factions are male. However, there are concept arts of female faction members during Global Offensive development.
- Prior to Counter-Strike: Global Offensive, players tend to prefer certain factions on certain maps in order to blend in with the environment, providing a semi-existent advantage (e.g. the preference of Arctic Avengers on snow themed maps like Office, Vostok, and Survivor due to their snow camouflage clothing). This advantage does not affect bots however as they are able to recognize players regardless of camouflage.
- In Global Offensive, all Counter-Terrorists use the same gloves except with different colors. For Terrorists, the Separatist, the Phoenix Connexion, the Balkan and the Professional use the same gloves, while all other Terrorist factions use different gloves.
- If the HD model pack is enabled in Counter-Strike 1.6, the player models will turn into Condition Zero ones, including the scientist hostages.