Why scripting ?
Tcl (pronounced "tickle" by some Unix weenies) stands for "tool control language," as Tcl was originally designed to be embedded inside applications on Unix and used as a scripting language for those applications.
Tcl's distinguishing characteristic is that it treats everything as a string of text. This slows down some things (don't try doing lots of math, for example) but also makes it easy to embed Tcl commands inside a Tcl program, a file, or an application.
To quote from the Tcl FAQ's answer to "What is Tcl?," "Tcl was designed with the philosophy that one should actually use two or more languages when designing large software systems. One for manipulating complex internal data structures, or where performance is key, and another, such as Tcl, for writing smallish scripts that tie together the other pieces, providing hooks for the user to extend."