Right now both [tag:throttle] and [tag:throttling] exist, with the larger batch of questions tagged with the [tag:throttle]. They seem to be be about the same general thing, and [tag:throttling] seems like a better choice to refer to the concept by. While that's being discussed, [tag: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](https://meta.serverfault.com/q/1703/40193), but the concept seems to be distinct and perhaps those tags should be removed.