From https://www.w3schools.com/css/css_boxmodel.asp
Explanation of the different parts:
Content - The content of the box, where text and images appear
Padding - Clears an area around the content. The padding is transparent
Border - A border that goes around the padding and content
Margin - Clears an area outside the border. The margin is transparent
Live example (play around by changing the values):
https://www.w3schools.com/css/tryit.asp?filename=trycss_boxmodel
