Every day millions of letters go from one country to another. Letters mailed in Italy are received in Japan. Letters mailed in Canada are received in Africa. On the letters are many different kinds of stamps,bought in different countries. The Universal Postal Union helps each letter get to the right place as quickly as possible. It sets up rules about the size and weight of letters,postcards,and small packages . It has rules that all countries must follow about international postal rates . One hundred years ago,international mail did not move so smoothly. One country did not always accept another country's letters. Letters from some countries were too large to fit into the mailboxes of other countries. Letters travelled by many different routes .Some were lost along the way. Sometimes the person who sent the letter could pay only part of the . The person receiving the letter had to pay the rest. The United States was the first to suggest that all countries work together to settle the questions of international mail. In 1974,men from twenty-four countries met in Switzerland to form the Universal Postal Union.Today,more than 120 nations belong to this union. From its office in Switzerland,the union helps the mail to move safely and quickly around the world. This passage is mainly about    _    .
different kinds of stamps in different countries an organization that makes rules international mail the size and weight of letters