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.
Simply, the specification for custom data attributes states that any attribute that starts with "data-" will be treated as a storage area for private data (private in the sense that the end user can't see it - it doesn't affect layout or presentation).
This allows you to write valid HTML markup (passing an HTML 5 validator) while, simultaneously, embedding data within your page
J. Almeida, and A. Simões. XATA 2006 --- 4ª Conferência Nacional em XML, Aplicações e Tecnologias Aplicadas, page 307--314. Portalegre, ESTGP, (Fev. 2006)