why is it a hashtag on twitter but a pound sign on your phone?

[Malibu]

anybody know why "they" decided to call the "pound sign" a "hashtag"?
Scott: thanks - i had the same thoughts about the pound tag and the hash mark name jumbling - i worked in computers when the internet was fairly new, and that "hash mark" was pretty much always known as the "pound sign" on a keyboard where i was - in the USA. you're right about it being a "null" line on a program where you could enter comments as long as you used the pound sign as a prefix.

[Scott]

Actually, it's the # that's called either a hash or a pound sign. Hash tag is a tag with a # (or hash mark) in front of it. It's really just convention that's it's called a hashtag and not a poundtag and that's it's called a pound sign on your phone. Generally in computing a # is called a hash sign. This is from certain programming languages that use the symbol, if I remember correctly, for commenting code. However, it would technically be just as valid to call a hashtag a poundtag and a pound sign on your phone a hash sign, it's just not the norm.