Google released a free HTML5 online book!
The book is called 20 Things I Learned About Browsers and the Web. According to the forward, it’s “a short guide for anyone who’s curious about the basics of browsers and the web.”
It covers the structure of the web, then offers primers in HTML, JavaScript and Ajax, then offers a glimpse at what’s next in the world of browsers and web apps. There are also discussions about privacy, security, open source software, and design.