Priority

I wonder what's the name of these stickers, which said "Priority" and posted on postcard or envelope. I don't know what are they called since I don't use that when I send mail or package abroad. Can anyone help me? Do you have to pay to get these stickers?

They're blue and are written in each country language. And they always get my attention. I love these stickers!!!

China

Finland

Slovakia

Vietnam

South Africa

Italy

Lesotho

Slovenia

Australia

Lithuania

Netherlands

Belgium

New Zealand

Estonia & Luxembourg

Chile

Belarus

Canada

Taiwan

United Kingdom

Budapest