Topic 1: Absolute vs. Relative
URL's are some of the most important elements in code, this is because they allow you to navigate the web from page to page, different pages within a site, and to certain parts on the site. There are two main types of URLs, absolute and relative. Absolute URLs are what we think of first, they are links that take the user to another website, absolute URLs contain the domain name as well as all other information to navigate to the designated site. Relative URLs are used when linking pages within the same site, and require less information because of this, you can omit the domain name altogether and only need to include the path from the current page to the new page.
Topic 2: Pixels, Percentages, and Ems
When deciding how to determine the dimensions of the box you just created you have three main options pixels, percentages, and ems, all of which have their perks. Pixels is the most common way to define dimension, this is because it allows you to be very accurate, it however does not scale with the screen. Percentages are used when you want the size of your box to be relative to the size of the screen or the containing box. Ems base the size of your box on the size of the type inside, it like percentages also scales with the screen as font size decreases.
Topic 3: Controlling Overflow
Overflow is described by the content of a box that deosnt fit in the designated space, there are two ways to handle it, hidden and scroll. Hiding your overflow causes anything that doesn't fit in the box to not appear on the screen at all, this can be helpful for keeping your site clean and ensuring no overlaps. The second way is scroll, and much like it sounds, if the content extends the bounds of its designated box then a scroll bar will be added to the box, allowing all content to still be viewed.