Ever wonder why SMS allows 160 characters, but Twitter – intended in part for use with mobile phones – only allows 140? No? Well pardon my nerd, I’m explaining anyway.
It’s more realistic to look at this as a limit on the number of bytes in the message. Most phones can only handle 140 bytes, which translates to 1120 bits (8*140). Mobile phones, it seems, use the standard ASCII character set which contains 7-bit characters. This allows 160 ASCII characters in the message. Computers, on the other hand, typically use 8-bit characters, putting us right back at 140 characters.
Now you know. But you probably still don’t care 🙂