Amazon is extremely helpful whether it is used or new books that you need. They also provide music and movies. I find that they have a better selection than most competing websites and better prices. For new items, the people of Amazon.com post the information themselves, but people that want to sell their items online can do so by making an account and posting the information about the item. Users can also write a review about any item they wish and about sellers that they have dealt with. The items are searchable by title, author, subject, and ISBN. The website then tells how many items it has found, if it has found more than one item of the same title you can choose which title is correct and then they will tell you how many matches they found, both used and new. Barnes and Noble is Amazon's largest competing website. Although I prefer Amazon, I do find that Barnes and Noble is easier to navigate and search for books. Also, sometimes the prices are better, especially with used and out of print books. However, Amazon does have a better selection, and most of the time they have better prices also.