Dive Into Accessibility is an excellent reading for people looking for an introduction to web accessibility. This book answers two questions. The first question is "Why should I make my web site more accessible?" If you do not have a web site, this book is not for you. The second question is "How can I make my web site more accessible?" If you are not convinced by the first answer, you will not be interested in the second.

Dive Into Accessibility is also a free e-book, written by Mark Pilgrim, and available for download as PDF and HTML format. If you have some free time and looking for a good reading, this is an excellent way to get yourself a great background into Web Accessibility.