Someone decided to introduce a revision tag, with the tag wiki:
Have you got an exam looming that you're worried about? Can't understand an important revision question? Need to brush up on one subject to help you study another? Use this tag and we'll do our best to help you help yourself, without us thinking it's homework.
This is quite clearly a meta-tag. Before I go ahead a nuke it (I really don't think there's a need for tags like such), I would however like to make sure that there has not been a discussion already about this tag with the community consensus being for its continued existence.
Thoughts or links to previous discussions?
Edit My reading of the link given by Lord_Farin below is that the previous time this came up for discussion the conclusion leans toward not having the tag. Unless there are further objections I will either kill the tag by manually retagging them or merging the tag into something else that is appropriate.