PuTTY is a terminal emulator application which can act as a client for the SSH, Telnet, rlogin, and raw TCP computing protocols. The name "PuTTY" has no definitive meaning[1], though 'tty' is the traditional name for a terminal in the Unix tradition, usually held to be short for teletype.
PuTTY was originally written for Microsoft Windows, but it has been ported to various other operating systems. Official ports are available for some Unix-like platforms, with work-in-progress ports to Classic Mac OS and Mac OS X, and unofficial ports have been contributed to platforms such as Symbian powered mobile phones.