It has several names, some confusing. The most common is probably Hash. In the US it is sometimes called the pound sign and used as a symbol for pounds weight, but this confuses the British for whom a pound sign is £. In music, of course, it is a sharp. The picturesque name octothorpe has also been introduced. It is said to have been invented by an employee of Bell Laboratories in the 1960s in Honour of the American athlete Jim Thorpe. In the large form in which it appears on modern telephones it is sometimes called square.
