This plugin was originally based on Acts as Taggable on Steroids by Jonathan
Viney. It has evolved substantially since that point, but all credit goes to him
for the initial tagging functionality that so many people have used.

For instance, in a social network, a user might have tags that are called
skills, interests, sports, and more. There is no real way to differentiate
between tags and so an implementation of this type is not possible with acts as
taggable on steroids.

Enter Acts as Taggable On. Rather than tying functionality to a specific keyword
(namely tags), acts as taggable on allows you to specify an arbitrary number of
tag "contexts" that can be used locally or in combination in the same way
steroids was used.