Tcl (Tool Command Language) is a basic programming language. It can be used by application programs as both a library package and as a language that gives simple commands to interactive programs. It is pronounced as "tickle".
Tcl was created in accordance with the idea that programmers should use at least two languages when designing large software systems. Since Tcl is a fairly simple language, it can be used when there are small tasks to accomplish. It is common to see the phrase Tcl/TK; TK refers to a ToolKit of widgets.