When can I use... : Compatibility tables for support of HTML5, CSS3, SVG and more in desktop and mobile browsers.
HTML5 Please : Look up HTML5, CSS3, etc features, know if they are ready for use, and if so find out how you should use them – with polyfills, fallbacks or as they
CSS3 PIE: CSS3 decorations for IE : Flexibility is a polyfill for Flexible Box Layout Module Level 1. Use it to design beautiful, flexible layouts on the web without sacrificing the expe...
320 and up : ‘320 and Up’ is a lightweight, easy to use and content first responsive web design boilerplate.
The HTML5 Shiv : The HTML5 Shiv enables use of HTML5 sectioning elements in legacy Internet Explorer and provides basic HTML5 styling for Internet Explorer 6-9, Safari...
So here we're collecting all the shims, fallbacks, and polyfills in order to implant html5 functionality in browsers that don't natively support them.