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Tcl stands for Tool Command Language. Tcl is really two things: a scripting language, and an interpreter for that language that is designed to be easy to embed into your application. Tcl and its associated graphical user interface toolkit, Tk, were designed and crafted by Professor JohnOusterhout? of the University of California, Berkeley. You can find these packages on the Internet (as explained later) and use them freely in your application, even if it is commercial. The Tcl interpreter has been ported from UNIX to DOS, Windows, OS/2, NT, and Macintosh environments. The Tk toolkit has been ported from the X window system to Windows and Macintosh.

Quote from the preface of

CategoryLanguage | Contributions by EelcoVisser