Scout units are the basic organizational structure of the Scouting movement. They are typically composed of a group of youth members, led by adult volunteers. The two most common types of Scout units are TROOPS (6 letters) and DENS (4 letters). TROOPS are typically organized by age and gender, and are led by a Scoutmaster. DENS are smaller groups within a Troop, and are typically organized by grade level. Each Den is led by a Den Leader.