A postcard is a piece of thick paper or thin cardboard, typically rectangular, intended for writing and mailing without an envelope. They are often used to send a brief message along with a pretty image, and are accepted as a form of mail worldwide. Postcards are typically made from a piece of thick paper or thin cardboard, and its common to write a brief message on one side along with the delivery address while the opposing side dawns a pretty image. They are often used when people are traveling and want to share a local view without writing a page-long letter. Postcards can be sent for various purposes, such as marketing a business, sharing good news, or spreading the word about an upcoming event. They are also used in school systems to teach students how to write their addresses and use local mail systems.