People are still reading plenty of books, but how and where they dig into a novel or a bit of historical non-fiction is changing.

Amazon is giving its Kindle app on iOS and Android a major overhaul to cater to the number of people who are reading and listening to books on their phones and tablets. The update, announced Tuesday, will roll out gradually and automatically replace the existing version of the app.

The app's biggest change is that it adds in more social options with Goodreads, a book reviewing community Amazon bought in 2014. The app also has a new design and a way to pin the book you're currently reading.

The new Kindle app still has one glaring omission on the iPhone and iPad: You can't actually buy a book. The only way to buy an e-book from Amazon (AMZN) on an Apple device is to log in to Amazon.com on the Safari web browser.

It's been a years-long issue between the two companies, which are in a stalemate over how much money Apple can take out of Amazon's e-book sales. Apple's policy is to take a 30% cut of any in-app purchases made through apps on its platform. That includes e-books, movies, music, and things like virtual stickers.

That's too much for Amazon. Mike Torres, a Kindle product director at Amazon, said the company is still waiting on acceptable business terms from Apple before it can add the feature.

Meanwhile, Android app users continue to be able to buy e-books through the app.

Kindle Unlimited subscribers, who pay $10 a month, can download millions of e-books. Amazon Prime members have access to more than 1,000 books and magazines through the app.

Related: Amazon finally made a waterproof Kindle

The new social features on the Kindle app are meant to keep people flush with reading recommendations. A tab shows an information feed about what your friends are reading and reviewing. You can see or share notes or highlights, and then comment on them. It's like a tiny book-centric Facebook. If you don't use Goodreads, you can still see activity here from popular reviewers or authors.

E-readers are dropping in popularity. According to Euromonitor, e-reader sales peaked in 2011 and have declined more than 40% since then. Amazon, however, claims last year was its best year for Kindle sales yet. It announced its newest Kindle, which is waterproof, earlier in October.

The company recognizes smartphones and tablets are a fast growing segment of its e-book business. People aren't just reading digital versions of their books on the devices either. Listening to audiobooks is becoming increasingly popular.

In the U.S., e-book sales dropped 15.6% in 2016, according to the Association of American Publishers. Audio book sales were up 25.8% for the year.