HTML5 Reference

So you want to learn about HTML5? You came to the right place.

Notable HTML5 Developers

There are a few people who are worth paying attention to due to the depth of their HTML5 development knowledge, or their ability to make HTML5 more understandable.

Jeremy Keith works at Clearleft, and wrote the brilliantly easy-to-read book HTML5 for Web Designers. He is a member of the HTML5 Super Friends, and when Zeldman decided to publish a book about HTML5, Jeremey Keith was the first person he called, based on how well he was able to explain HTML5 to the rest of the Super Friends. (follow him on twitter)
Bruce Lawson works at Opera, and wrote the book Introducing HTML5. He's converted his personal blog to HTML5, and is a regular contributor to HTML5 Doctor. (follow him on twitter)
Mark Pilgrim works at Google and is writing the book Dive into HTML5 for O'Reilly, which you can read online for free. (follow him on twitter)

Free HTML5 Web Resources

Some of the best sites, blogs, and links I've found for learning HTML5

HTML5 Rocks Slides: This entire slide deck is made using HTML5, so it serves as a learning tool and a demo all rolled into one.
Dive Into HTML5: Mark Pilgrim is writing an HTML5 book for O'Reilly, and he's got the working draft up for anyone to read. Probably the best free resource available for someone looking to learn.
HTML5 Doctor: A blog written by several big names in the HTML5 community, including Bruce Lawson. There are articles written on just about every new HTML5 feature, and new content is added frequently.
Bruce Lawson's Blog: A great example of how to use HTML5 markup for a blog. Bruce was kind enough to put up his template for download.
HTML5 Shim: The nice little javascript file that will enable HTML5 for IE users. Now hosted on google code for faster load times!
HTML5 Outliner: If you want to test the outline that HTML5 generates from your sectioning elements, here's the tool to do it.
WHATWG FAQ: A FAQ about HTML5 from the WHATWG. Sometimes it's nice to get answers right from the horse's mouth.
W3C HTML5 Web Developer's Guide: An edited version of the HTML5 spec, intended for web developers, rather than browser manufacturers.
Using WAI-ARIA Landmark Roles: Nice explanation of what WAI-ARIA roles line up with HTML5 elements, and why you should use them.
HTML5 Browser Support Checklist: These type of browser support charts are notoriously unreliable (for example, they all say that IE6 doesn't support PNG files, but there are many ways to work around this). Still, it's a nice overview of what's well-supported, or to help prove the point that HTML5 is ready to use today.

Books About HTML5

If you don't mind spending some money, these are some of the best books on the subject.

HTML5 for Web Designers by Jeremy Keith: The first book published under Zeldman's A Book Apart label, this book should be first on your shopping list for several reasons. First, it's cheap. For only $18, it covers everything you'll need to know to get up and running. Second, it's easy to read -- both because it's short (only 85 pages) and because it's funny and well-written. I cannot recommend this book highly enough.
Dive Into HTML5 by Mark Pilgrim: This book was just published by O'Reilly, but you can still read it for free(!) on the website. It's very well-written and an excellent resource. I've read the whole thing online, and plan to pick up a hard copy soon. (amazon)
Introducing HTML5 by Bruce Lawson and Remy Sharp: This is an good book, and it only pales slightly in comparison to the other two. One of my objections is simply that the book is printed on incredibly cheap, thin paper, that makes the reading experience slightly tedious. While the other two books strike a more conversational tone, this is more of a reference book. (amazon)

Download the Slides

You can download Scott's slide deck (PDF, 1.4 MB) for reference. This presentation is titled "HTML5 and Drupal Theming" but is a good HTML5 introduction for anyone, not just Drupalers.