This video explains about good syntax. He also says that 'whitespace' is used to help the user read code.
<head> <p>A paragraph</p> </head>
So the spaces, or 'tabs' (actually, in most program text editors, you can use the tab button to create a long space) is really optional. You can get the same output with this, but it is much harder to read an uglier:
<head><p>This is bad text</p></head>
Also, he teaches about a few extra tags. The <section> tag and the <article> tag. This can be used for ordering:
<section> <p>This section is for comments!</p> </section>
The tag can be used the same way. And he goes through a little CSS too. He talks about ids and what they can do. Lastly, he teaches about "genetic tags". When you target the tag with, let's say, a color of green, this targets the body tag AND any tag inside it. It's really interesting because it is very similar to real life genetics. Here is an example:
<grandmother eye="blue"> <mother> <son> </son> </mother> <aunt> <cousin> </cousin> </aunt> </grandmother>
If the grandmother had blue eyes everyone inside would have blue eyes, unless they were specifically changed to another color. If you gave the body a color of blue, then the body and everything inside would be blue.