Oh, and another thing (#tag)

['Hashtag' oddness - part 2]

This thing here - # - is not a 'hashtag'. It's a 'hash' (as they used to tell you on the more complicated kinds of phone-calls), also known as the 'pound sign', 'number sign', and even, apparently, the 'octothorpe'.*

A hashtag is the hash sign followed by the cutesy commentary. #likeitsaysinthisOEDdefinitionrighthere

See?

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* which makes perfect sense, but this is the first I've heard of it.