Skirmishers are soldiers who engage in a minor or preliminary combat in front of a larger force. There are several synonyms for this term such as scouts, guerrillas, scouts, sentries, vanguards, pickets, and advance guards. These words all refer to soldiers who are sent out ahead of the main force to observe, engage, or protect. Scouts are typically used for reconnaissance or intelligence gathering, while guerrillas are associated with irregular warfare or ambush tactics. Sentries are soldiers who are posted in a specific location to observe and defend that area. Vanguards and advance guards are the lead elements of a military force, responsible for reconnaissance and securing a forward position. Pickets are soldiers stationed at an outpost or along a defensive perimeter.