The hashtag was invented by Chris Messina, a programmer and open source advocate, in August 2007 as a way of flagging up the salient features of a tweet. He took the hash sign, which had meant ‘number’, and made it mean ‘important concept-alert’. The hashtag’s use in tweets has now developed a style and language of its own. They’re everywhere, punctuating Twitter and Instagram jokes, Facebook posts and other forms of communication. I like making stupid hashtag neologisms, but I’m probably not alone in feeling uneasy about the way they boil large bodies of information down to a couple of words. There is, of course, something brutally reductive about them, and the word ‘tag’ has overtones of criminality or pricing: available for search, available for purchase.