Ingroup refers to the group you belong to and identify with when your group is interacting with another group. For example, when two rival sports teams face off in a game, the team you support is the ingroup, while the other team is the outgroup. Ingroup identity also factors into interactions between different races, nationalities, social classes, and so on. Attitudes and behaviors toward the ingroup tend to be more positive than toward the outgroup.
See also: Outgroup