An "in-group" refers to a social group with which an individual identifies and feels a sense of belonging. Members of an in-group often share common interests, values, or characteristics, which can create strong bonds and a sense of community. This group can be based on various factors, such as ethnicity, religion, or shared hobbies. In contrast to the in-group, there is an "out-group," which consists of individuals who do not belong to the in-group. This distinction can lead to favoritism towards in-group members and sometimes prejudice against out-group members. Understanding these dynamics is important in fields like sociology and psychology.