The working class is a social class broadly composed of people who are primarily involved in blue-collar or manual occupations, typically involving physical labor and often in industries such as manufacturing, construction, transportation, and agriculture. Membership in the working class is often defined by the type of work performed and may be associated with lower levels of formal education and income compared to the middle or upper classes. Historically, the working class has played a significant role in industrial societies, and their labor is essential for the production of goods and services. The term can also encompass those in lower-skilled service sector jobs. While the specific boundaries and characteristics of the working class can vary across different societies and over time, it generally refers to individuals and families who rely on wages or salaries from manual or less skilled labor for their primary source of income and who may have less economic security and social mobility compared to other social classes.