The `padding` CSS property sets the padding area on all four sides of an element. This property can be used to generate space around content (inside the border) to improve readability of the content inside. It is a shorthand to set all individual paddings at once: `padding-top`, `padding-right`, `padding-bottom`, and `padding-left`. Values are defined in the clockwise direction and are most often specified in pixels, although percentages or ems can also be used. If a percentage is used, the padding will be a percentage of the browser window or of the container it is found in.
Padding values are set using lengths or percentages or `inherit` keyword, and cannot accept negative values. The initial, or default, value for all padding properties is 0. While you can use `inherit` keyword, it can not be used with a length value. The `padding` property value is not inherited by the child elements like the `color` value of the `font-family` property is, so the padding must be specified for each element that requires it.
The padding property in CSS defines the innermost portion of the box model, creating space around an element's content, inside of any defined margins and/or borders.
Do note, while padding and margins are similar in the context of 'adding spaces between elements', padding is **included** into the element's dimensions, while margins are not.