Sociology is the study of groups and group interactions, societies and social interactions, from small and personal groups to very large groups. A group of people who live in a defined geographic area, who interact with one another and who share a common culture is what sociologists call a society. Sociologists study all aspects and levels of society. Sociologists working from the micro-level study small groups and individual interactions, while those using macro-level analysis look at trends among and between large groups and societies. For example, a micro-level study might look at the accepted rules of conversation in various groups such as among teenagers or business professionals. In contrast, a macro-level analysis might research the ways that language use has changed over time or in social media outlets.