Which CSS property is used to create space on the outside of an element?

The correct choice is the property that is specifically designed to create space around an element, outside of its border. This property allows for the adjustment of space that separates an element from adjacent elements, effectively providing a cleaner layout and improving readability in web design.

Margin can control the space on all four sides of an element (top, right, bottom, left), allowing for precise positioning relative to surrounding elements. By applying margin, you can create vertical and horizontal gaps that can enhance the visual structure of a webpage without affecting the dimensions of the elements themselves.

Understanding the distinction between margin and other properties is crucial. While padding deals with space inside an element (between the content and the border), and border defines the outer edge of the element itself, margin focuses solely on the external spacing. Background-color, on the other hand, is used to define the element's color and does not pertain to spacing. Thus, margin is the property that specifically meets the requirement of creating space outside of an element.