All of our templates are coded using HTML5. HTML5 is a major revision of the HTML standard. It's really the HTML we're all used to, just with more elements.
Special Note: While Expression Web 4 will display HTML5 elements correctly in Design View, earlier versions of Expression Web will not. While you can use an HTML5 template in an earlier version, you will not be able to rely on Design View for how your page accurately looks.
But HTML5 isn’t one thing. It is a whole collection of features and technologies. Most features are cross-browser compatible and ready for prime time, so the good news is most parts of HTML5 we can use right now.
For instance, you can change your doctype to the HTML5 one (<!doctype html>). Your document is now HTML5. Because the HTML5 spec was based on a lot of work figuring out what browsers already do, things like this work. So, if you prefer the HTML5 syntax, feel free to do that now.
Note that unknown HTML elements are displayed as inline by all browsers, so we've added display: block; for new block-level elements in the main CSS file for older browsers.