Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
While you should instead use the CSS border-spacing property, the obsolete HTMLTableElement interface's cellSpacing property represents the spacing around the individual <th> and <td> elements representing a table's cells. Any two cells are separated by the sum of the cellSpacing of each of the two cells.