This week we'll teach you how to implement dynamic tooltips -- the small yellow bubbles that pop out in many applications. They appear when you move the cursor over a tool button or a designated text segment and vanish when the cursor is removed from the object. Tooltips are attractive to the user because they provide additional information about a given object, without cluttering the screen with unnecessary data. Tooltips are powerful because they are context sensitive.

By now you're probably looking for our traditional front page demonstration. Simply head to the top of the page and move the cursor over the "home / experts / javascript" directory structure, without clicking any of those links. You'll find a different tootip for each link. Play around with this technique, while studying its most obvious characteristics. For example, the tooltip always appears directly below the pointer. In this column, you will learn:

1. How to construct a tooltip with HTML.
2. How to define a stylesheet for each tooltip on the page.
3. How to associate a tooltip with a specific link via its event handlers.
4. How to find out when the tooltip should be displayed.
5. How to display a tooltip when required.
6. How to clear a tooltip when the user removes the pointer from the link.
7. How to associate a tooltip with multiple links that share the same URL.

We'll show you how to implement tooltips in two different ways. At this point you may choose to view the code for the first and second methods.