A schema is a cognitive structure that serves as a framework for ones knowledge about people, places, objects, and events. In psychology and cognitive science, a schema describes a pattern of thought or behavior that organizes categories of information and the relationships among them). Schemas are mental models found in long-term memory that allow the brain to organize information about the world. They are recognition devices whose processing is aimed at evaluating how well new information fits into itself. Schemas can be changed and reconstructed throughout a person’s life through assimilation and accommodation. Examples of schemas include mental models, social schemas, stereotypes, social roles, scripts, worldviews, heuristics, and archetypes). In Piagets theory of development, children construct a series of schemata, based on the interactions they experience, to help them understand the world).

It is important to note that the term "schema" is also used in the context of database management systems. In this context, a database schema defines how data is organized within a relational database, including logical constraints such as table names, fields, data types, and the relationships between these entities.