I’ve been aware of Americans’ using the term ‘pound sign’ when talking about Twitter hash tags, and I was always confused by it. I came to the conclusion that they called it that because on the MacBook Pro keyboard (UK English) there is actually no # symbol visible anywhere. To get it, I hold down the alt key (option key for Americans – why do you do that, Apple?) and 3, which just happens to be the £ key when using shift.
Then this morning my daughter was watching the Rancho Relaxo episode of the Simpsons (Homer Alone – S03E15), Troy McClure uses the term ‘pound sign’ to get an extension on a phone. I always though that was a joke, in other words, call 1-800, then the pound sign, then 456, meaning that it would cost you £456 for the call. It never dawned on me that for that to be funny it would most likely be a dollar sign and that there IS no pound sign on a phone.
So this use of ‘pound sign’ to mean # predates Twitter and I’m not sure what the UK-English Mac keyboard had on it in 1992 or whenever that episode was written.
The “#” sign is referred to as the “hash symbol” in the UK, but it is sometimes called the “pound sign” in non-Sterling countries (though in reference to the unit of weight, not the unit of currency). It is also known as the number symbol or key.
The symbol “£” is in the MacRoman character set and can be generated on most non-UK Mac OS keyboard layouts which do not have a dedicated key for it, typically through Option+3. On UK Apple Mac keyboards, this is reversed, with the “£” symbol on the number 3 key, typed using Shift+3, and the number sign (“#”) generated by Option+3.
I still find it strange to hear ‘pound sign’ for hash tag. Weird.