W3C Markup Validation Service, a free service that checks Web documents in formats like HTML and XHTML for conformance to W3C Recommendations and other standards.
“For people who make websites” A List Apart Magazine explores the design, development, and meaning of web content, with a special focus on techniques and benefits of designing with web standards.
For the sake of your (search engine) Quality Score, (human) Credibility and (financial) bottom line, there are exactly six pages your site must include.
Web Design from Scratch is for everyone involved or interested in creating web sites - whether novice or expert. It will help you understand what makes web sites succeed or fail, and what can be done to increase the chance of success.