Serial servers are used to connect serial devices to a Local Area Network (LAN) / Wide Area Network (WAN) without additional hardware. Serial servers can be used as terminal servers, remote access servers, and modem pooling devices. They are also used to transparently extend server serial ports over LANs in Unix, Linux and Windows environments. For the most part, serial servers are stand-alone devices (not built into an existing system), designed for desktop or rack mounting.