A catalog is a list or record of items. As the diagram suggests, a catalog commonly refers to a list of things being offered, such as items for sale or courses at a school. A catalog chart or catalog diagram serves as a guide to the collection of materials acquired for the library. It also serves users as a retrieval tool. There are several types of catalogs like author catalog - a formal catalog is sorted alphabetically according to the names of authors, illustrators, or editors and subject catalog - a catalog that is sorted based on the subject. The main purpose of catalog charts is the ability to reach hundreds of thousands of readers with minimal cost. It dramatically increases a retailer’s exposure to potential shoppers.