Right now both throttle and throttling exist, with the larger batch of questions tagged with the throttle. They seem to be be about the same general thing, and throttling seems like a better choice to refer to the concept by.

While that's being discussed, rate-limiting should probably be thrown in the mix as being an alias candidate for the same concept.

All of the above tags are sometimes used in conjunction with network bandwidth tags discussed in my previous question, but the concept seems to be distinct and perhaps those tags should be removed.