Thin clients are small, networked computers that use centralized servers and do not include CD-ROM drives, disc drives or expansion slots. Most data processing occurs on the server.

Only the keyboard input, screen output, and client-server communications and authentication occur on the thin client. For network administrators, thin client computing can reduce costs and overhead by eliminating disk drives, drive arrays and other data storage devices. Thin clients are also a popular alternative to traditional client/server architectures because of factors such as enhanced security and network efficiency. Bulk licensing for thin clients is a cost-effective alternative to purchasing, installing, and maintaining a large number of software licenses on various user PCs. Thin client computing is also cost-effective in terms of data backups, centralized security, and load balancing.

There are many types of thin clients. Examples include X Window terminals, Web farm clients, and independent computing architecture (ICA) clients. A Citrix thin client is used in applications such as Citrix MetaFrame and WinFrame. The graphical user interface (GUI) of a Citrix thin client provides support for UNIX, Java, Windows and Macintosh applications, as well as browser architectures such as Internet Explorer, Netscape Navigator, Mozilla and Firefox. A Windows terminal service (TS) is another GUI-driven architecture in thin client technology. Windows TS converts a Windows NT or Windows 2000 server into a shared, thin client computing system via remote desktop protocol (RDP). In turn, all of the client machines become thin clients and function as dumb terminals. Overlaying a Citrix MetaFrame on Windows TS enables the ICA protocol to support other client architectures such as UNIX, Linux, and OS/2.

A Linux thin client uses the Linux operating system (OS), a popular focus of the software open-source movement. Applications for Linux thin clients are available from vendors such as Red Hat, Hewlett-Packard, Novell and IBM.