Money, borders, citizenship and the rules of a game are everyday examples: they are real in their effects, but they exist because people share the belief and behave accordingly. Sociologists use the idea to show how categories that seem natural can vary across cultures and over time.
Debate arises when the idea is applied to categories such as gender or race. Many scholars argue that the meanings and social roles attached to these categories are socially constructed, while others stress that biology also plays a role and that treating something as constructed does not make it unreal or unimportant. Positions often follow political lines, but the underlying questions are empirical and philosophical.