If you buy something using links in our stories, we may earn a commission. This helps support our journalism. Learn more. Please also consider subscribing to WIRED The equal sign is the bedrock of ...

The hash symbol – also known as the pound/number sign, or even the octothorp(e) as Macworld reader Keith points out – was one of the more rarely used special characters until Twitter and Instagram ...

In some programming languages, the number sign (#), also called the "pound sign" and "hash sign," is used as a not-equals symbol. For example, the expression if amount # 500 means "if amount not equal ...

From the Romans to Twitter, the hash sign – or octothorpe – has had a rich history, and now this innocuous little character has found a mighty resurgence as the hashtag. What happened along the way?