What is the CSS box model?

Every element of HTML is surrounded in a customizable CSS box which consists of: margins, padding, borders and the content of HTML.

What is the difference between margin and padding?

Margin is the space outside the border of the element while padding is the space in between.

How is an HTML element height and width determined?

With the use of "height" and "width" tags

Explain the CSS property: padding 25px 50px

This element would have top padding of 25px and right padding of 50px.

What is the difference between border and an outline?

Borders take up space and can only be squares or rectangles while outlines don't take space and can be non-rectangular.