Why can't the tag contain a tag inside it?

Question

As far as I know, this is right:

  
some words

But this is wrong:

  &l         


        

Answer 1

After the X HTML, the conventions has been changed, and now it's a mixture of conventions of XML and HTML, so that is why the second approach is wrong and the W3C validator accepts the things correct that are according to the standards and conventions.