In social studies, a "union" typically refers to a
labor union, also known as a trade union. This is an organization of workers who have banded together to achieve common goals such as better wages, benefits, working conditions, or job security. They act collectively to negotiate with employers (often referred to as "management") through collective bargaining. The power of a union comes from its members' ability to collectively withhold their labor (strike) if their demands are not met.
While "union" can sometimes refer to other forms of collective action or organizations in different social contexts, the most common meaning within social studies is related to labor unions and their role in shaping worker rights and the economy.