In a word: reading. The Nook Simple Touch with GlowLight allows you to download and read books and documents in EPUB or PDF formats. (Full list of file types supported: EPUB, PDF, PNG, JPG, GIF, and BMP.) You can highlight and annotate EPUB documents. The E ink display simulates a print reading experience; the embedded Glow Light illuminates the E ink screen, allowing you to read in the dark.
You'll find few if any ebooks already loaded on the Nook when you check it out. However, you can load ebooks from a variety of sources onto the Nook. How you get books onto the Nook depends on a few factors: the biggest is whether the ebook you want to download is protected by digital rights management (DRM).
Adobe Digital Editions (ADE) is free software that lets you download and manage ebooks and documents that are protected by Digital Rights Management. Two major sources of DRM ebooks are eBook Academic Collection (provided by Marlboro College) and, if you are affiliated with a public library that offers, it, Overdrive. Before transferring DRM ebooks to the Nook, you'll need to download, install, and configure ADE on your own computer.
You can connect the Nook to a computer (using the included microUSB cable) to load non-DRM-protected EPUB or PDF files. The Nook will appear on your computer as a removable drive. Just click on the file on your computer, and copy it (drag-and-drop) to the appropriate Nook folder.
Here are some sources of free ebooks that you can download to your computer and transfer to the Nook.
When you borrow the Nook, it will be registered to the library's Barnes & Noble account. If you leave the device registered to the library, you'll be able to see the few (if any) books that the library has purchased and downloaded from the Barnes and Noble Nook Store. You won't be able to purchase new content or download free sample chapters. You will, however, be able to load content to the Nook using Adobe Digital Editions or drag & drop, as described in (1) and (2), above. Anything that you load to the Nook will be erased upon its return.
If you have your own Barnes & Noble account, you are welcome to deregister the Nook from the library's account and register it to your account. You should then be able to download any Nook books that you own to the Nook. When you return the device, we will restore it to factory settings and re-register it to the library's account. Anything that you buy and download to the library's Nook will be erased from the Nook, but should remain available for you in your B&N account.