The study of group dynamics is important because groups are important. Our relationships with groups pervade almost every aspect of our lives. We are raised in families and educated in schools. Most of us work in a group setting and many of us live in families of our own. Moreover, we all live in a community, belong to one or more ethnic groups, and are categorized into a specific gender. Groups shape our daily life, powerfully influence our identity and self-esteem, and even shape our very perception of the world around us. Consequently, our psychology and the brain that creates it have evolved to promote our participation in groups.