ncurses is a library for screen and terminal handling. It includes basic functionality that was traditionally supplied by libraries like termcap such as clearing the screen and changing text colors It also has support for more sophisticated pseudo-GUI elements like text based menus and windows.

It is part of the GNU project and is thus licensed under the GPL. It is a standard part of any linux system I've ever encountered. It (or one of its equivalents) is commonly used for anything from running a shell to menuconfiging the linux kernel.

The current version is 5.3. However, it is actively maintained and there are official patches to this which are essential if you're using gcc-3.x, compiling for a powerpc, or like secure, stable software. The latest patch, as a gziped shar is available at ftp://dickey.his.com/ncurses/5.2/something.sh.gz