Paperback books are a type of book that has a flexible cover made of paper or cardstock. They are typically lighter and more affordable than hardcover books, making them a popular choice for readers. The pages are usually printed on thin paper, which helps keep the overall weight down. These books come in various sizes and formats, including mass market paperbacks and trade paperbacks. Mass market paperbacks are smaller and often found in stores, while trade paperbacks are larger and usually of higher quality. Both types are widely available and cater to different reading preferences.