Box Model or Block Model
- margin
- border
- padding
- content
A more detailed look:
block-start, block-end, inline-start, inline-end
For LRTB writing, these correspond to top, bottom, left, and right.
Think about the block axis (direction of multiple lines) and the inline axis (direction of line)
Image from CSS: The Definitive Guide, 5th ed by Eric Meyer and Estelle Weyl, published by O'Reilly