** Description ** A [Tcl] extension adds to the standard functionality of the Tcl interpreter. Extensions are written in [C] using the Tcl [API], and are often distributed as part of a [package] that often includes [script%|%scripts%|%] to facilitate the use of the extension. An extension may define new actions, new [widget]s, new processing types, etc. ** See Also ** * [Tcl Extension: User Guide] * [Tcl Extension: Developer Guide] * [Extensions for Tcl and Tk] * [Writing Extensions] * [package] * [extension language] <> Glossary