This will set the bottom padding of the object. It takes the following values. a) pt : You can set values in points. (e.g: 10pt or 100pt). b) px : You can set values in pixels. (e.g: 10px or 100px). c) % : You can set values in percentage. (e.g: 10% or 100%). d) auto : This will set a automatic margin.
Note: The difference between padding and margin is that padding set values inside the objects scope, while margin moves the whole object away from the nearby object.