Language is a system of spoken, written, or signed symbols and the rules for combining them to communicate meaning. It is the most powerful and flexible tool humans have for sharing information, coordinating action, and transmitting culture.

Every human society has a language, and children acquire the language of their community with striking speed and uniformity. Languages differ in vocabulary, sound system, and grammar, yet all are capable of expressing an open-ended range of ideas. The productivity of language—the ability to generate and understand sentences never heard before—distinguishes it from the more limited communication systems of other species.

Psychologists study language at multiple levels: the perception and production of speech sounds, the recognition of words, the parsing of sentences, and the extraction of meaning in context. Disorders such as aphasia reveal the neural specialization that supports these processes. The relationship between language and thought remains an active area of research and debate.

Language turns private experience into something that can be offered to another mind.