Simply put, sociology is the study of groups of people. Sociologists want to know how social groups are formed and how they are maintained. Sociologists are interested in studying the behavior of social groups of all sizes, ranging from groups as small as families to those as large as nations, or the population of the world as a whole. Sociologists are interested in learning about all sorts of groups, including street gangs, worker's cooperatives, high school students, single working mothers, immigrants, and corporate executives. Any time that people come together to pursue common goals, whether for a single day or a lifetime, sociologists want to discover how individuals influence the actions of groups and how groups influence the actions of individuals. In order to do this, sociologists examine the interactions among members of groups as well as the collective actions of groups as they interact with other groups.