This field manual provides a doctrinal framework on how Infantry rifle platoons and squads fight. It also addresses rifle platoon and squad non-combat operations across the spectrum of conflict. Content discussions include principles, tactics, techniques, procedures, terms, and symbols that apply to small unit operations in the current operational environment (COE). FM 3-21.8 supersedes FM 7-8, Infantry Rifle Platoon and Squad, dated 22 April 1992 (with change 1, dated 1 March 2001). It is not intended to be a stand-alone publication. To fully understand operations of the rifle platoon and squad, leaders must have an understanding of FM 3-21.10, The Infantry Rifle Company, and FM 3-21.20 (FM 7-20), The Infantry Battalion. The primary audiences for this manual are Infantry rifle platoon leaders, platoon sergeants, and squad and fire team leaders. Secondary audiences include, instructors in U.S. Army Training and Doctrine Command (TRADOC) schools, writers of Infantry training literature, other Infantry leaders and staff officers, and Reserve Officer Training Candidate (ROTC) and military academy instructors. Infantry leaders must understand this manual before they can train their companies using ARTEP 7-8 MTP, and ARTEP 7-8 Drill. They should use this manual as a set along with the publications listed in the references. The Summary of Changes list major changes from the previous edition by chapter and appendix. Although these changes include lessons learned from training and U.S. Army operations all over the world, they are not specific to any particular theater of war. They are intended to apply across the entire spectrum of conflict. This publication applies to the Active Army, the Army National Guard (ARNG)/Army National Guard of the United States (ARNGUS), and the United States Army Reserve (USAR) unless otherwise stated.