In a move that should please publishers, the September release of iOS 8, Apple’s updated operating system for phones and tablets, included the integration of the iBooks app. Now all new Apple mobile devices will come with the app, and access to the iBooks store, pre-installed, ready for potential e-book buyers to use.

The integration comes as Apple ramps up efforts to reach new e-book consumers and enhance opportunities for discovery and promotion in the iBooks store, which it hopes to position as a major online retailing channel. Apple has sold more than 550 million iPhones and more than 237 million iPads, and its impact on the e-book market will continue to grow. The release of the iPhone 6 and 6 Plus, both with significantly larger and more reader-friendly screens than their predecessors, will likely attract readers of heavily illustrated and media-rich digital books, as well as textbooks.

The iBooks store, which can be accessed through the iBooks app, has added new features, including a selection of free e-books and additional categories to help consumers find the books they want. The titles offered in the “Great Free Books” section represent a variety of genres and reading tastes. Among them are Private by James Patterson and Maxine Paetro (a thriller), Pretty Little Liars by Sara Shepard (a YA novel), How the García Girls Lost Their Accents by Julia Alvarez (literary fiction), Justice League, Vol. 1: Origin by Geoff Johns and Jim Lee (a graphic novel), and Lost in Shangri-La by Mitchell Zuckoff (nonfiction). The free books also include three titles that are exclusive to Apple: Be My Love by Lucy Kevin (a romance novel), The Animal Book by Steve Jenkins (a reference title), and an interactive edition of Jane Austen’s Pride and Prejudice, with video content and study guides.

The YA and new adult are fast-growing categories on the iBooks Store, Apple said. The store frequently tinkers with its featured All Categories page, adding topical and seasonal categories pages for mainstay categories like Fiction, Nonfiction, Mysteries, Arts & Entertainment, Biographies & Memoir, and Comics & Graphic Novels. Each section displays a carousel highlighting specific titles or collections. The online book retailer has also looks to create a number of topic categories that link books to related movies, TV shows, and music offered via iTunes. While some categories have been discontinued, such as Breakout Books, which launched in early 2013 to promote self-published titles in the iBooks store; Apple said it is continuously experimenting, adding new features and updating older ones to drive discovery of indie authors on the site.

Last week the All Categories page highlighted a rotating selection of topical categories, including If You Like Gone Girl, Trick or Treat, and National Book Awards 2014 Finalists. The store also has a series of pages called Author Spotlights that are each focused on the works of a hot author. Other pages include Bestsellers Priced at $3.99, Books Made into Movies, Award-Winning Books, and Sneak Peeks, which lists big forthcoming books available for preorder.

Apple makes use of its physical retail store locations to promote the iBooks store. Calling it “sharing the ecosystem,” Apple noted that recent Meet the Author events at Apple’s SoHo store in Manhattan featured bestselling YA novelist John Green, comics artist Jim Lee, Batman writer Scott Snyder, actress and author Gillian Anderson, and designer Tory Burch, with more events to come.