rollover

In creating page for a Web site , a rollover (some people call it a "mouseover") is a technique using JavaScript that lets you change a page element (usuallly a graphic image) when the user rolls the mouse over something on the page (like a line of text or a graphic image). The term rollover recognizes that there is a little ball in your mouse that you roll on a surface.

Some common uses of the rollover include:

• Inviting user interaction by causing text elements in a menu to "pop up" or otherwise become lively as you roll the mouse over each line. This is done by creating a small graphic image for each text line and a second graphic image for each line that is substituted when a given text line is rolled over with a mouse. The effect invites users to click on one of the rolled over lines.
• Causing a previously invisible graphic image or other element to suddenly appear when the user rolls the mouse over a particular page element. Raymond Pirouz's home page site for his book, click here , uses this technique. Try it.
• Have one element on a page change color as you roll the mouse over other elements. It's a way to reinforce the user's recognition that certain page elements are "alive" and clickable.