Postcards are printed on a paper backing that allows the images to be printed on the back of the card itself.

Postcards usually come in a variety of sizes, from one inch to several inches across.

Many are sold in postcard stores, and many retailers offer a variety online.

The images are often embedded with logos that help identify them as postcards.

Some postcard manufacturers use a type of sticker to help identify the product.

Some types of postcards are marketed for use in postcards, while others are used for advertising and promotional purposes.

The postcard advertising business has been growing since the early 2000s.

Postcard makers have expanded their business by producing advertisements for products and services that customers can buy.

The Postcard Advertising Association, an industry trade group, estimates that in 2017, there were more than 20,000 postcard makers.

The trade group reports that postcard-based marketing accounts for more than $300 million in sales, with an average annual revenue of $1.7 million.