Wikipedia features 3 type oftooltips: inline tooltips added by editors, page preview tooltips for wikilinks, and reference tooltips.
Editors can add inline tooltips to articles using the{{Tooltip}} template, like so:{{Tooltip|The text|The tool tip}} which makes it appear like this:The text.
The{{Abbr}} template can be used for abbreviations. Tooltips are also used by various templates. For instance, the{{obsolete source}} template, here shown with a tooltip reason:[obsolete source].
In general, editors should use inline tooltips selectively such as when they're useful fortable column headers. (SeeMOS:NOHOVER for information)
Editors should check that tooltip text renders as intended. For instance, if the tooltip text includes a " character, the tooltip is cut short.
When hovering over a link to another article, a short summary of the subject and an image (if available) is displayed as a tooltip.
When hovering over a reference, a tooltip appears that shows the full reference.