Gangs are street thugs that are involved in numerous crimes such as murder, theft, counterfieting, and other things. Gangs are usually headed by a leader, although some gangs don't have a leader and operate on their own, and known to carry various types of weapons.
Gangs are usually always active night and day. They can be seen walking the streets or hanging out in groups. Certin gangs can only be found in certin areas of the city (Haitians in Little Haiti, or Cubans in Little Havana.) Some gangs can be involved in wars with rival gangs, and sometimes the police.
Gangs thoughout the city arn't usually hostile to the player unless the player attacks the gang causing the gang to attack the player back. Gangs will only attack the player if the player targets them or fires at them, or if the player has a bad reputation with a gang. Sometimes the gang will ignore you if the host of the group doesn't have a gun. If the host of that group has a gun, then they will attack the player.
The gang host leads their entire group that they are in, deciding whether to attack rival gangs and where to go. Some gangsters in that group, including the host may or may not be armed with a weapon. If the host has a weapon, its likely that the their group will attack rivals or the player, is he or she has harmed them or the player is very well hated by them.
Some gangs have vehicles that they use, some prefer to patrol the streets on foot. Usually, the types of vehicles depend on the gangs style. If a particular gang is dressed in 80's type clothing, the vehicles will most likely to be older, of if the gang is wealthy, the vehicles will range in the more expensive type, like sports cars.