Zero client

A thin client is a lightweight computer that is purpose-built for remoting into a server (typically cloud or desktop virtualization environments). It depends heavily on another computer (its server) to fulfill its computational roles. This is different from a conventional desktop PC (fat client), which is a computer designed to take on these roles by itself. The specific roles assumed by the server may vary, from hosting a shared set of virtualized applications, a shared desktop stack or virtual desktop, to data processing and file storage on the client's or user's behalf.

Thin clients occur as components of a broader computing infrastructure, where many clients share their computations with a server or server farm. The server-side infrastructure makes use of cloud computing software such as application virtualization, hosted shared desktop (HSD) or desktop virtualization (VDI). This combination forms what is known today as a cloud based system where desktop resources are centralized into one or more data centers. The benefits of centralization are hardware resource optimization, reduced software maintenance, and improved security.

Thin client hardware generally consists of a computer terminal which provides I/O for a keyboard, mouse, monitor, jacks for sound peripherals, and open ports for USB devices, e.g. printer, flash drive, web cam, card reader, smartphone, etc. Some thin clients include legacy serial and/or parallel ports to support older devices such as receipt printers, scales, time clocks, etc. Thin client software typically consists of a GUI (graphical user interface), cloud access agents (e.g. RDP, ICA, PCoIP), a local web browser, terminal emulations (in some cases), and a basic set of local utilities.

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 trade-offs of using cloud architecture and thin clients is that the host becomes a single point of failure. If the hosting server crashes, for example, all users lose their session unless a fail-over process is predefined. This risk can be mitigated by building redundancies into the host environment. Redundancy provides reliable host availability but adds cost to the cloud computing model. Redundancy can be provided in the form of networked servers, clustered file systems, load balancing, etc.

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