HTML5 takes a much more flexible approach than XHTML did. HTML5 is designed with the idea that authors have been writing HTML in many different ways over the years and there are zillions of web pages out there that don't adhere to the strict XHTML standards. Rather than render those page useless, let's just relax the standard a bit (well, a whole lot). They call this "paving the cowpaths."
As an example of this flexibility, all of the following are permitted in HTML5:
As the above shows:
This new flexibility could lead to a bit of chaos on your development team. Different HTML authors will take different approaches. Our recommendation is that you choose one approach and stick to it. In this course, for example, we use the following guidelines:
Again, it doesn't matter so much which guidelines you choose, but it'll make your life easier if you specify some. If you're a big XML fan, you're more than welcome to stick with XML syntax described above and create XHTML5 pages.