These days, good old fashioned books are called 'treeware.' This is because so many books - both classics and brand new releases from big imprints - are available in electronic format.
These treeless books are called ebooks. Many years ago, Project Gutenberg spearheaded a movement to get public domain titles scanned, proofed, and released for free on the Internet. Thousands of volunteers took books (old enough to be out of copyright) and turned them into electronic files so they can be easily indexed and accessed by anyone with Internet access.
Today, Project Gutenberg hosts thousands and thousands of public domain titles you can download and read for free. These books can be read directly on your computer, or using a portable electronic device (like a palmtop computer, ebook reader, or a cell phone).
If you love to read, or would enjoy electronic access to the classics, check out
Ebook Software for your PC: