concept

A concept is an abstract idea that underlies and unifies a category of objects, properties, or relations. It functions as a mental representation that enables thought, communication, and inference. Concepts can be simple or complex and are often expressed in language as words or phrases. They are central to philosophy, cognitive science, linguistics, and artificial intelligence, where they support classification, reasoning, and explanation.

The term concept comes from Latin conceptus, from concipere “to take in, seize.” In classical philosophy, concepts were viewed as the content of universal ideas. In modern usage, a concept is understood as a mental representation with a set of defining attributes (intension) and the things it denotes (extension). Researchers analyze how concepts are formed, organized, and used in thought and language.

Cognitive theories identify several ways concepts can be stored and learned: feature-based or rule-based definitions; prototype theory, in which a central example anchors the category; and exemplar theory, which relies on remembered instances. A concept typically has an extension (the objects it covers) and an intension (the attributes or properties it conveys). Concepts may vary in precision and can be graded by typicality.

In practice, concepts enable categorization, generalization, and communication across contexts. They are essential in knowledge representation, education, and human-computer interaction. Challenges include vagueness and boundary cases, context dependence, and linguistic polysemy, all of which affect how a concept is understood or applied. Despite these issues, concepts provide a foundational mechanism for organizing information and guiding inference.