The examples below show the variety of "Content" source you can use in your tooltips:

Mouse over this link to see a tooltip with some simple text.

Mouse over this link to see a tooltip with some text with html formatting.

Mouse over this link to see a tooltip with full html code.

Mouse over this link to see a tooltip with an image as content.

Mouse over this link, or this link to see two different tooltips with the 'title' attribute of their link being their content.

Mouse over this link to see a tooltip with some simple text and a title.

Click on the following links to see tooltips that contain Youtube videos:

The Black Knight Video (click)   Argument Clinic Video (click)

Mouse over this link to see a tooltip that loads another HTML file as content, using the AJAX technique.