Mail art is like sending a letter to your friend, but more fun and creative. You can decorate the envelope and add pictures or stickers to it. You can also make the letter itself look cool by drawing on it or using different colors. People who make mail art like to be very creative and make their letters special and unique. And just like regular mail, you put a stamp on it and send it in the mail. It's a fun way to make someone smile when they get your special letter!