Debuting in Max Payne 3 and carrying over to Grand Theft Auto V, Crews go beyond traditional online clans by allowing players to join large public Crews or simply create a private Crew that members can customize.
In this way, Crews help players keep the fight alive from match to match - and even across titles - through the Rockstar Games Social Club, which will keep track of Crew stats and Feuds.
http://www.rockstargames.com/newswire/article/23171/multiplayer-crews-revealed-on-ign-play-from-max-payne-3-to-grand.html
