The language originated as a common language for semiconductor design tools. Ousterhout saw that a number of design tools he was involved with all had ad hoc l

The language originated as a common language for semiconductor design tools. Ousterhout saw that a number of design tools he was involved with all had ad hoc languages, so he developed Tcl as a single common solution to the 'scripting language problem'. This is partly why the language is designed to be as easily embeddable as it is. Post this origin, Tcl developed a modicum of broader fame through Tk (one of the best/easiest early X11 toolkits) and expect (which is a tool for automating control of command line interactive tools).