Tooltips in MathJax

This page is a summary, expansion, and working example of the topic ‘Labeling equation terms’ from the MathJax Users Group in April 2011.
It includes solutions that were contributed by Davide P. Cervone.

There is a known bug that affects the positioning of the tooltips, which may be fixed soon.

There are four versions of tool tips:

Although this capability is not built into MathJax, it is easy to obtain by following the instructions on this page
(and using the source code of this page as an example).