The definition of Tcl/Tk

The Tool Command Language is a portable interpreted computer language designed to be easy to use. Tk is a GUI toolkit for Tcl. Tcl is a fairly popular language for both integrating existing applications and for creating Web applets (note that applets written in Tcl are often called Tcklets). Tcl/Tk is available for free for most platforms, and plug-ins are available to enable many browsers to play Tcklets.