It's a #socialmediaproblem. You're poised at your computer, fingers hovering over the keyboard, wanting to send a witty tweet or post a selfie. But wait, you're on an unfamiliar Apple Mac, external ...

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 ...