The CSS box model is a rectangular layout paradigm for HTML elements that consists of the following:
- Content - The content of the box, where text and images appear
- Padding - A transparent area surrounding the content (i.e., the amount of space between the border and the content)
- Border - A border surrounding the padding (if any) and content
- Margin - A transparent area surrounding the border (i.e., the amount of space between the border and any neighboring elements)