According to the Justice Department's complaint, the five publishers were unhappy that competition from Amazon was driving down the price of e-books. Amazon had set the price of all of its e-books at $9.99.
When Apple launched its iBookstore along with the release of its first iPad, the publishers agreed to give Apple 30 percent of the revenue from the e-books it sold. Additionally, they gave Apple the "most-favored nation" status, which guaranteed that no other retailer could sell an e-book for less than Apple.
The agreements drove up the price of e-books, including the ones in Amazon's Kindle Store, by about $2 to $3 per book, according to the Justice Department.
The settlement requires the publishers to abandon their agreements with Apple and to allow other retailers, such as Amazon and Barnes & Noble, to discount their books.