A network computer is a lightweight computer system that operates exclusively via a network connection . As such, it does not have secondary storage such as a hard disk drive – it boots off the network, and it runs applications off the network, possibly acting as a client for an application server. During the mid to late 1990s, many commentators, and certain industry players such as Larry Ellison, predicted that the network computer would soon take over from desktop PCs, and everyone would use applications over the internet instead of having to own a local copy. So far, this has not happened, and it seems that the network computer "buzz" was either a fad or not ready to happen.

The idea actually goes back a long way however, back to the text-only dumb terminal, and later to the GUI of the X terminal. The former needed no software to be able to boot, everything was contained in ROM, and operation was simple. The latter requires some files to boot from the network, usually using TFTP to get them after obtaining an IP address via DHCP and bootp . Modern implementations include not only the X terminal, but also the Terminal Server in Microsoft Windows 2000 and XP, and others. The name has also evolved, from dumb terminal to network computer, and now to thin client.