This manual is based on the premise that although the unit organization, weapons systems, and conditions have changed, antiarmor company and platoon maneuver, fire, and movement have not changed. FM 3-21.91 (FM 7-91) provides doctrine for employing the antiarmor company and platoon. It contains guidance on tactics and techniques that antiarmor companies and platoons use in offensive, defensive, stability, and support operations. This manual borrows from "nested" concepts found in FM 7-10 and FM 71-1 and reemphasizes information from other manuals that are of critical importance. The target audience includes antiarmor platoon leaders, company and battalion commanders, and battalion staff officers. This manual provides training developers with the combat-critical tasks and missions of antiarmor companies and platoons, and it enables combat developers to refine and revise operational concepts for antiarmor organizations.