Client Computers can be classified as Fat Client, Thin Client or Hybrid Client.

Fat / Thick 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.

It was originally known as just a "client" or "thick client," later the name was contrasted to thin client, which describes a computer heavily dependent on a server's applications.

A Fat Client or Thick Client is a client that performs the bulk of any data processing operations itself, and does not necessarily rely on the server. Thick clients do not rely on a central processing server because the processing is done locally on the user system, and the server is accessed primarily for storage purposes. For that reason, thick clients often are not well-suited for public environments. To maintain a thick client, IT needs to maintain all systems for software deployment and upgrades, rather than just maintaining the applications on the server.

For example – Personal Computer.

Thin Client

A thin client is a lightweight computer that has been optimized for remoting into a server-based computing environment. The server does most of the work, which can include launching software programs, crunching numbers, and storing data.

A Thin Client use the resources of the host computer. A thin client generally only presents processed data provided by an application server, which performs the bulk of any required data processing. A thin client machine is going to communicate with a  central processing server, meaning there is little hardware and software installed on the user's machine. A device using web application (such as Office Web Apps) is a thin client.

Hybrid Client

Hybrid client may either just mean diskless node, or it may be used in a more particular sense to mean a diskless node which runs some, but not all, applications remotely, as in the thin client computing architecture.

Advantages of diskless nodes can include lower production cost, lower running costs, quieter operation, and manageability advantages (for example, centrally managed software installation).