Example of a large tooltip from the Ikariam Wiki's Dump page
Tooltips are simple hover effects you can use to provide extra information to readers when they hover over certain elements on a page, such as text.
Step by step
In order to make a basic tooltip all you will have to do is surround the text you wish to have a tooltip with div or span tags containing the parameter title="text goes here!", like this:
<span title="This is a tool-tip!">Mouse-over me to see the tool-tip!</span>
or
<div title="This is a tool-tip!">Mouse-over me to see the tool-tip!</div>
To produce this (using the span tag):
Mouse-over me to see the tool-tip!
You can also change the way the cursor looks when hovering over the same text or any other text by adding style="cursor:<cursor-style>;". For example: