padding

Sets the padding around an element, in a percentage (not recommended), relative measurement, or pixels. Resembles the cellpadding table attribute.

Usage:

style="padding: 2px 3px 2px 3px;"

expands to:

style="padding-top: 2px;padding-right: 3px;padding-bottom: 2px;padding-left: 3px;"

NOTES:
It's redundant, but use both the shorthand AND longhand formats when defining padding.
Trouble (TRBL) is a good acronym for remembering the rendering order for margins, padding, and borders.