A mouseover, sometimes termed a rollover, is a bit of programming — typically JavaScript — that creates a different effect on a web page, when the mouse rolls over a certain object or part of the page (like a segment of the text). The simplest mouseover can do things like changing the color of the text if your mouse rolls over that text. Yet mouseovers no longer have to be simple things. Rolling the mouse over part of the page can produce exciting graphics or changes in existing graphics or text.
Much of the early Internet was considered flat and non-interactive. This changed with the development and release of a new programming language called JavaScript in 1995. Quickly, Netscape Communicator 2.0 was released, which could interpret JavaScript. As a result, many programmers used JavaScript to create more exciting web pages.
![](http://images.wisegeek.com/slideshow-mobile-small/man-in-suit-using-computer-mouse.jpg)
Yet you can find mouseover examples off the Internet too. Lots of programs featured changes by merely rolling over part of a screen. Many games, in particular used them. A mouseover can also be referred to as a GUI or graphical user interface. You’ll find computer games for children and adults, and even more business-oriented programs use mouseover or GUIs to develop more interesting effects without all that clicking or double clicking.
The code for creating a rollover can differ depending upon what type of effect you want to create. Essentially with JavaScript, you’re accomplishing something called object oriented programming. This can be defined as creating code that interacts with other pieces of code in a program.
One very simple mouseover example, that you’ll see repeated again and again on Internet pages like Wikipedia and on wiseGEEK, is a slight change in color, and perhaps an underlining of certain words on text that is clickable (that might take you to another page or another site). As you’re reading a wiseGEEK page you’ll note if you use your mouse that simply moving the mouse over certain text will cause that text to become lighter-colored. Most computer users know this means they can click on the text to explore a link to elsewhere.
Mouseovers certainly don’t need to be quite that simple. WiseGEEK also uses mouseovers that bring up small windows, with advertisements. They don’t obscure your reading the text, and they can give you information about products or services available to you that are related to the subject you’re reading about.