I built a website www.creditunionautorates.com , I was wondering if using html5 would allow the site to be displayed on multiple platforms?
Designing in HTML 5 will help a little, but it's no miracle worker. The structure is still similar to HTML 4, it just uses new tags to differentiate areas of the website. A combination of this and media queries will help you: http://css-tricks.com/resolution-specific-stylesheets/
Responsive Web Design: http://coding.smashingmagazine.com/2011/01/12/guidelines-for-responsiv e-web-design/
North America
Europe, Middle East and Africa
Asia Pacific