Digital Rights Management (DRM) is technology that controls access to, tracks, and limits uses of digital works.

The technology is part of the digital item and goes along with it when it is distributed to the consumer.

• American Library Association (ALA) description of DRM
• Wikipedia's article about DRM
• Electronic Frontier Foundation view
• Consumer's Guide to Digital Rights Management

FREELY AVAILABLE

If a book is “in the public domain,” it means that it is not protected by copyright and anyone can use it.

• These ebooks can be downloaded from sites listed here and many others.

• Once downloaded, these ebook files are yours forever. They do not have DRM.

LOANED BY LIBRARIES

Public Libraries -- Many public libraries provide ebooks via a service called Overdrive. To check out ebooks from your county library, you must have a library card from them, and you must download Overdrive Media Console onto your reading device. These books have DRM.

Academic Libraries such as Sewanee's  – Ways of access differ depending on what the publisher or vendor requires.

• Some ebooks must be read online via a web application or proprietary software reader.
   
• Another example is the Proquest Ebook Central service, to which Sewanee subscribes. You must read Proquest ebooks with software or an app, because they have DRM (Digital Rights Management) protection. Among other functions, DRM controls the length of time that an ebook can be viewed after you check it out.

AVAILABLE THROUGH PURCHASE OR LICENSE

• Many companies, such as Amazon.com, Barnes and Noble, Google Play, and Buy.com sell ebooks that you can buy.
   
• Once downloaded, these ebook files are supposed to stay on your device for as long as you want them.
  
  But be aware that sellers have the ability to “take them back” – there have been a few cases in which books licensed through Amazon disappeared from their owners' Kindle readers AFTER being bought. If you buy or license an ebook with any DRM controlling access to it, make sure you know how long your access is supposed to last. (Remember that what you are usually paying for is a license to access the content of the book, not ownership of the book itself.)