Hi. <ul> and <li> are tags covered in the “basic HTML andd HTML5” section of Responsive Web Design. <ul> forms the wrapper for an unordered list, and you can add bullet points inside with <li> see here
<nav> is covered in the “Applied Accessibility” section of Responsive Web Design <nav> is a semantic element that wraps around a collection of <a>, how it is used is up to the discretion of the coder. It could contain a collection of internal links to various sections, or external links to other relevant pages. There can be more than one <nav> in one page as well. See here
in this specific instance:
nav has no styles in CSS.
nav ul (the ul elements that are descendents of nav elements) has its margin/padding set
nav li (the li elements that are descendents of nav elements) has its display changed from list-item to inline so it will be side by side with its sibling li, also removing the bullet points, and the added margin-right ensures space between the siblings.
Uh… I knew those already, I’m just wondering about the navigation bar, lists and stuff like that in the code. (See the preview in the challenge? I’m asking about the nav bar)