Audio books are are a great way to catch up on all the books you want to enjoy but don't have time to read. You can listen to them while you jog, or on long car rides / flights or while you cook and clean, but the only problem is that they tend to be more expensive than the print editions of the same book. For example, the Divergent unabridged audio edition is $14.95, and a used copy of Divergent in paperback is only $5.95 on Amazon.com. Even with shipping costs the print edition is cheaper, but that's where Audible comes in.
Audible is a subscription-based service from Amazon.com which gives members access to more than 150,000 audio book titles. If you listen to a lot of audio books, an Audible membership may be something you want to consider.