Groups can vary drastically from one another. For example, three best friends who interact every day as well as a collection of people watching a movie in a theater both constitute a group. Past research has identified four basic types of groups which include, but are not limited to: primary groups, social groups, collective groups, and categories. It is important to define these four types of groups because they are intuitive to most lay people. For example, in an experiment, participants were asked to sort a number of groups into categories based on their own criteria. Examples of groups to be sorted were a sports team, a family, people at a bus stop and women. It was found that participants consistently sorted groups into four categories: intimacy groups, task groups, loose associations, and social categories. These categories are conceptually similar to the four basic types to be discussed. Therefore, it seems that individuals intuitively define aggregations of individuals in this way.