In computer networking, a thin client (sometimes called a slim client or lean client) is a simple, low-performance computer that has been optimized for remote desktop connections to a server-based computing environment. In some cases, they are also referred to as network computers or, in their simplest form, zero clients.

The server performs most of the workload, including launching software applications, processing computations, and handling data storage. This contrasts with a rich client or a traditional personal computer — the former is designed for a client–server model but retains significant local processing power, while the latter performs most of its functions locally.

Thin clients typically operate as part of a larger computing infrastructure — often involving a server farm or cloud-based system — where many clients share centralized resources. The server-side infrastructure may use application virtualization, hosted shared desktop (HSD), or desktop virtualization (VDI). This model forms a centralized cloud computing environment hosted in one or more data centers.

Key advantages of centralization include:

Thin client hardware typically supports common peripherals, such as keyboards, mice, computer monitors, audio jacks, and open USB ports (e.g., for printers, flash drives, webcams). Some models include legacy serial ports or parallel ports to support specialized equipment such as receipt printers or time-clocks.

Thin client software commonly includes:

In using cloud-based architecture, the server takes on the processing load of several client sessions, acting as a host for each endpoint device. The client software is narrowly purposed and lightweight; therefore, only the host server or server farm needs to be secured, rather than securing software installed on every endpoint device (although thin clients may still require basic security and strong authentication to prevent unauthorized access). One of the combined benefits of using cloud architecture with thin client desktops is that critical IT assets are centralized for better utilization of resources. Unused memory, bussing lanes, and processor cores within an individual user session, for example, can be leveraged for other active user sessions.

The simplicity of thin client hardware and software results in a very low total cost of ownership, but some of these initial savings can be offset by the need for a more robust cloud infrastructure required on the server side.