Tags are keywords or descriptive terms used to classify requirements. They provide a more flexible, free-form way to group together related requirements (compared to using pre-defined categories).

Tags are used in Accompa to display similar requirements, as well as in searches.

A Tag Cloud is a visual depiction of all the tags entered by users on your system, where font size indicates popularity - i.e. more popular a tag, bigger the font size. For more information on tag clouds - check out this Wikipedia article.