If we are talking about CSS layout then the first thing is the CSS box model which provides proper layout structuring and makes layout flexible. These are some properties that come under the box model like margins, padding, borders, and content that we need in layout to display users.
Margin –Margin will take space from outside, example: if we set 10px margin in div then next content will start after 10px.
Padding – Clears an area around the content. The padding is transparent
Border – A border that goes around the padding and content
Content – Where text and photos will appear
The image below is an example of a box model: