Twin (acronym for "Textmode WINdow") is a windowing environment with mouse support, window manager, terminal emulator and networked clients, all inside a text mode display.Twin supports a variety of displays: plain text computer terminals (any termcap/ncurses compatible terminal, the virtual console, Twin's own terminal emulator);X11, where it can be used as a multi-window Xterm; itself (it is possible to display a Twin on, or "inside", another Twin);twdisplay, a general network-transparent display client, used to attach/detach more displays "on the fly".Twin is tested on Linux (x86, PowerPC, DEC Alpha, SPARC) and on FreeBSD; porting to SunOS is in progress.