Number sign is a name for the symbol #, which is used for a variety of purposes including, in some countries, the designation of a number (for example, "#1" stands for "number one"). The symbol is in Unicode as code point ; it is also present in ASCII with the same value.
In the United States, the symbol is usually called the pound sign and the key bearing this symbol on touch-tone phones is called the pound key. In Canada, this key is most frequently called the number sign key. In most other English-speaking countries the symbol is usually called the hash, and the corresponding telepho...