A skirmish (noun)is a small battle or engagement, such as might happen when a patrol met another patrol.

Skirmish (verb) is also related to how troops might be used. This has to do with lose groupings of troops moving forward to test the location and strength of where the enemy might be. Instead of mass lines of troops, such skirmishers would be spread out, with 10-20 feet between them maybe.

Skirmishing might taking place as part of a larger battle and is distinct from scouting. Scouting is about obtaining information. Skirmishing is associating with fixing the location of formed enemy units and screening the movement of friendly troops.