An e-book, or electronic book or digital book, is a book that is either an electronic version of a printed book or a book that was born digital, and which is accessable on a computer, e-reader or other mobile device.
These are some of the most common e-book formats that you will encounter:
See these Wikipedia pages for more information about e-readers and e-books:
These are also good sites:
Connecting to Yale's electronic resources remotely from off campus using VPN
Requesting an item in print from Yale Borrow Direct and Interlibrary Loan
Other technical support offered at Yale: