A paperback (also known as softback or softcover) is a type of book press-printed and covered with stock paper characterized by a thick paper or paper board cover, and often held together with glue rather than stitches or staples. In contrast, hardcover or hardback books are bound with cardboard covered with cloth; although more expensive, hardbacks are more durable.
They are affordable and completely flexible in both build and functionality. Get more information here.
Although Soft Cover books are the most popular, they are not as durable as hardcover books. Because the reader can curl up in their bed or comfy chair, fold the cover and pages back as it is being read add to its popularity. Also, Soft cover books are more easier to transport. They fit inside of tight spots such as a purse or a pocket depending on the size of the book.
Last but not least, they are less expensive when mailing Soft Cover books due to cost of shipping usually being determined by the weight of the package being shipped.