Fat client

A fat client (also called heavy, rich or thick client) is a computer (client) in client–server architecture or networks that typically provides rich functionality independent 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 characterised 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.

Introduction

In designing a client–server application, a decision is to be made as to which parts of the task should be executed on the client, and which on the server. This decision can crucially affect the cost of clients and servers, the robustness and security of the application as a whole, and the flexibility of the design to later modification or porting.