Class (concept)

Common senses

• Social class: divisions of people or households by economic position, status, or power.
• Educational class: a group of students taught together or a single lesson period.
• Programming class: in object-oriented programming, a blueprint that defines data and behavior for objects.
• Biological class: a taxonomic rank in biology between phylum and order.
• Mathematical class: concepts such as an equivalence class or a proper class in set theory.

In social sciences, "class" is used to describe socioeconomic strata and differences in access to resources. Analysts consider income, occupation, education and social status to explain patterns of inequality, political behavior, and cultural life. The term can be applied descriptively (to name observed groupings) or analytically (to test theories about how such groups form and matter).

In education, a "class" commonly refers to a cohort of students (for example, the graduating class of a given year) or to a scheduled lesson. These uses emphasize organization and time structure: classes organize instruction and learning environments for logistical and pedagogical reasons.

In computer science, a class is a construct that encapsulates data (attributes) and operations on that data (methods). Languages that support object-oriented programming use classes as templates to create instances (objects), and features like inheritance and polymorphism let programmers express relationships and reuse code.

Mathematics and logic use "class" in more technical ways. An equivalence class groups elements that are equivalent under a relation; a proper class in set theory denotes a collection too large to be a set (for example, the class of all sets). These precise meanings are defined within formal frameworks.

History and distinctions

The English term traces back to Latin classis, originally meaning a division or levy. Over time it evolved into multiple related senses of grouping and rank. Important distinctions across uses include whether membership is fixed or dynamic, whether the grouping is social or formal, and whether it is descriptive or prescriptive. Because "class" carries different technical implications in different disciplines, writers and speakers clarify context to avoid confusion.