Gaps are small spaces between paths. If paint leaks through and paints faces you did not intend, you probably have a gap in your artwork. You can create a new path that closes the gap, edit existing paths to close the gap, or adjust the gap options in the Live Paint group.
This command highlights any gaps found on the currently selected Live Paint group, based on your gap options settings for that group.
If gap detection is off in all groups in the selection, gaps are closed and gap detection is turned on with Paint Stops At set to Small Gaps.
If gap detection is on and the same for all groups in the selection, gaps are closed and the gap setting is preserved.
If gap detection is mixed for the selection, gaps are closed and the gap settings of the bottommost Live Paint group are preserved (if gap detection is on for that group). If the bottommost group has gap detection turned off, gap detection is turned on and Paint Stops At is set to Small Gaps.