A common graphical user interface component, consisting of a permanently visible row of button icons which, when clicked with the mouse, cause the program to perform some action such as printing the current document or changing the mode of operation.

The tool bar buttons often duplicate functions accessible via menus but are easier to use since they are permanently visible. A typical use would be in a paint program where the tool bar allows the users to select one of the various painting "tools" - brush, pencil, bucket etc.

Some application programs under some operating systems may allow the user to customise the functions accessible via toolbars, in others the choice is fixed by the programmer.