From a sociological perspective, groups are fundamental to understanding human social life. Sociology studies how humans interact, communicate and construct social collectivities. Groups exist in every society—whether ancient, feudal or modern, Asian, European or African—though the types of groups differ across societies.

Not every gathering of people constitutes a social group. Aggregates or quasi groups are simply collections of people who are in the same place at the same time but share no definite connection with one another. Examples include passengers waiting at a railway station, airport, bus stop or a cinema audience.

Sociologists categorize groups into different types based on a pattern in the typology. They contrast how people form groups in traditional, small-scale societies with those in modern, large-scale societies. Traditional societies are marked by close, intimate, face-to-face interaction, while modern societies are characterized by impersonal, detached, distant interaction.

This distinction leads to the classification of primary groups versus secondary groups, and community versus society or association. Through ongoing social interaction, individuals come to understand and assume social roles. Concepts like stratification reflect the concern sociologists have in understanding the structured inequalities between groups in society.