In a graphic user interface, such as a Web browser or a Gopher client, the fact that the user can use a mouse to point at portions of the image or text and click on that point. Once the user clicks on a point in the display, the client launches an action, either following a hypertext link or running another program. WWWebfx Home Page

Something that responds somehow when someone clicks n it with the mouse.

refers to an icon, a picture map, an underlined anchor or any other object in an webpage which allows the user to interact with the browser by using the button on the mouse.

a series of photos which, when taken in sequence, simulate some sort of movement or action.

This describes a feature on a page that, when clicked, starts an action. For example, clicking on a word or graphic might follow a hyperlink or start another application.