Reference Sites
These are some of my favorite web design reference sites. They are great resources for searching syntax, browser support and best practices.
Can I Use?
This an incredible useful reference site for checking browser support and best practices
HTML5 Rocks
In-depth resource for learning HTML5, with a specific emphasis on the available APIs. Features tutorials, articles and downloadable resources.
HTML5 Doctor
HTML5 reference site that focuses on the proper semantic implementation. Contains a quick HTML5 element reference guide, articles and other resources.
Mozilla Developer Network
Comprehensive resource for all things web. Contains articles on learning web design basics, references for HTML, CSS, and JavaScript and much. Indispensable resource for web designers.
Stack Overflow
Free online Q&smp;A community for web designers and developers. Although the quality of answers can vary, it's usually a good place to start when troubleshooting.
Web Platform Docs
Community-driven site that is attempting to become the standard web development documentation reference. Contains a wealth of information including the current status of various web specifications.