can you elaborate on the difference between descendant and child

"What is the difference between a parent/child relationship and a ancestor/descendent relationship. 
based on this code:
<ul>
   <li>harry</li>
   <li>ron</li>
   <li>hermione</li>
   <li>malfoy, who is a <em>pureblood</em></li>
</ul>

I'm not sure why <em> is not a child but a descendent."

I would like to talk more about descendants.

More about the difference between the selectors

Inheritance rules; more complex selectors 

Can you discuss more about the next sibling selector versus the sibling selector 

pseudoclasses!


I don't have any questions for the reading, but can you explain question 2 on this quiz in detail?

how to choose which structural selectors to use? 

none at the moment! / None at the moment, the reading was clear.