What does <div> do?


I got the main point about "div class". It group code for more neat code.
But I couldn't get the difference between "nav" vs "container".
Didn't they both include whole ul code?


class="nav" and "container" are referring to different css style. please refer nav and container tag in css.


Aw I see , I don't have any css background and just started this course. Should I learn sth first ?


just take basic knowledge of html,css and js from any tutorial.


CSS is coming up in the next section of this course. You might benefit from working through the HTML & CSS course first.