The term context menu is commonly used for menus which pop up when clicking an item in a graphical user interface, offering a list of options which vary depending on the context of the action, the application running, and the item selected. These menus are typically invoked with a secondary mouse button (usually the right-hand button) on a computer running an operating system such as Microsoft Windows, Mac OS X or Unix running the X Window System. Computers with a single-button mouse may use a keyboard-click combination, as with a Control-click in the Macintosh OS. PC keyboards with Microsoft Windows keys also have an additional menu key that opens context menus in Microsoft Windows applications.

Context menus first appeared in the Smalltalk environment on the Xerox Alto computer, where they were called pop-up menus. The NEXTSTEP operating system further developed the idea, incorporating a feature whereby the right or middle mouse button brought the main menu (which was vertical and automatically changed depending on context) to the location of the mouse, thereby eliminating the need to move the mouse pointer all the way across the large (for the time) NextStep screen.

Context menus are sometimes hierarchically organized, allowing navigation through different levels of the menu structure. The implementations differ: Microsoft Word was one of the first applications to only show sub-entries of some menu entries after clicking an arrow icon on the context menu, otherwise executing an action associated with the parent entry. This makes it possible to quickly repeat an action with the parameters of the previous execution, and to better separate options from actions.

Context menus have received some criticism from usability analysts when improperly used, as some applications make certain features only available in context menus, which may confuse even experienced users (especially when the context menus can only be activated in a limited area of the application's client window).

In some applications, like newer versions of Microsoft Office, some of the "infrequent" items in the context menu are hidden by default. This is subject to criticism as users have to expand the menu before accessing items which are classified as infrequent items (which may not be as infrequent as assumed).