It’s gone by many names, (the pound sign, the number sign, the octothorpe and the hashtag symbol) and it’s had many meanings, but what is the origin of this # mysterious symbol?

Other than the pound sign, it is also known as a number sign, mainly in America. In the UK, we call it hash (from “cross-hatch”), but it has a wealth of other, more fun, names, including crunch, ...