xhtml is dynamic html, html that includes javascript and other active elements.
html5 is the latest ratified version of html, consider html like a work in progress:
- html 1.0 (things get deprecated)
- blah
- blah
- blah
- html5
with each new version of version of html things get deprecated (become obsolete an are removed from the next version). Long story short just learn HTML5 it's just not all of the features in it are backwards compatible with older browsers.
w3schools.com (best place for getting the basics out of the way)
Some advice:
- you'll want to learn css, it's how they made websites look all pretty, and when you learn it get into the habit of using external stylesheets, never use inline styles, embedded is ok for testing purposes or one off changes.
- Chrome is the most compatible browser with HTML5 and CSS3 standards as seen here:
http://www.findmebyip.com/litmus/
as you may notice IE is the ***** of the group, microsoft continues the trend of saying screw the rules we have money. Design your websites previewing with chrome, and fix your IE hassles later.