A fat client, also known as a thick client or rich client, is a computer in a client server configuration that can function independent of the server. Many applications are installed locally on the client hard drive. While a fat client pulls some data from the central server and needs to be connected to the server sometimes, it can run on its own, without having to always be connected to the central server.
Fat client architecture is an alternative to thin client computing. In a thin client environment, all of the applications and in some instances all of the processing power are provided by the server computer. A thin client can be a computer that accesses and runs applications directly from the server or it can be a simple terminal machine that provides no processing of its own. The fat client or thick client is a computer that has its own storage, memory and processing. When trying to decide between a thin client and thick client environment, important considerations include the applications to be run, the graphic requirements for each terminal and the portability and scalability needed.
Some of the advantages of fat clients are reduced load on the server and the ability to work independently of the central server, while being able to deliver rich functionality. Because the output is generated locally, fat clients allow richer graphical user interfaces (GUIs). A fat client can also run faster than a thin client, especially with resource-intensive applications, since fat clients store many applications locally. Program information is written to and accessed from local computer resources instead of having to be transmitted across the network infrastructure.
The use of fat clients is becoming more prevalent. This is due in part to decreasing computer and software licensing costs. It has become much more cost effective to deploy a fat or thick client onto each desktop than to continue adding resources to a server to accommodate an increasing number of terminal machines.
One common implementation of a fat client environment is the use of corporate laptops. While docked, or connected remotely, to the internal network, these computers can utilize the resources stored on a central server. They can also be taken out of the network environment and still be used as standalone computers to run locally installed applications. However, they are not able to access documents that are stored on the server and may only be able to use some applications, such as email programs, in an offline mode.