Stamp collecting is one of the most popular collecting hobbies in the world. Young people, old people, rich people, and poor people in every country collect stamps. Stamp collecting has been called "the hobby of kings and the king of hobbies." King George V of the United Kingdom, Franklin D. Roosevelt, and many other famous people have collected stamps. Students of stamps are called philatelists. The name comes from two Greek words, philos, meaning loving, and atelos, meaning free of tax, or paid. Stamps are signs that the postage, or tax, has been paid.