Fat client

A fat client (or rich client) is a computer (client) in client-server architecture networks which typically provides rich functionality independently of the central server. Originally known as just a "client" or "thick client", the name is contrasted to thin client, which describes a computer heavily dependent on a server's applications.

A fat client still requires at least periodic connection to a network or central server, but is often characterized by the ability to perform many functions without that connection. In contrast, a thin client generally does as little processing as possible and relies on accessing the server each time input data needs to be processed or validated.