Locate and note your book's ISBN number. Find this 10 or 13 digit number on the back cover of a book near the barcode or UPC symbol.
Determine the condition of your book. Books in "excellent" or "like new" condition will fetch the highest price; such a book must be in immaculate condition without any defects on either the book's cover or its interior. A book in "good" condition may show minor signs of wear such as folds or scratches. The term "fair" condition applies to books with greater signs of wear including highlighting and handwritten margin notes. Books in "poor" condition, also known as "reading copies," are worn to the point where their covers may be falling off or pages may be ripped. Books in poor condition may be challenging to sell.
Note any additional information that a buyer may wish to know about your book, such as "small tear on page three," etc.
Type "sell secondhand textbook" or "sell used textbook" into an Internet search engine and click "search."
Consider your results. Companies dedicated specifically to book buyback include Powell's Books, Cash 4 Books, We Buy Textbooks and Book Jingle. Also consider BookScouter, which works for textbook retail much like the website Kayak does for airfare -- it searches other book-buying websites to find the best price for your specific book.
Explore websites such as Amazon or eBay. Amazon offers two methods of sale. The first is book buyback, in which Amazon will exchange your book for an Amazon gift card in a predetermined amount. The other option is to sell your book to an individual buyer on the general Amazon marketplace, setting the price as high or low as you wish. On eBay, you always pick the price at which to sell your book. Here, you may choose to sell via an online auction or the Buy It Now option, which allows buyers to purchase the item instantly at the price you've set.