Special Forces (SF) or Special Operations Forces (SOF) are highly-trained military units that conduct specialized operations such as reconnaissance, unconventional warfare, and counter-terrorism actions. Some Special Forces operations, such as counter-terrorism actions, may be carried out domestically under certain circumstances. Special Forces units are typically composed of relatively small groups of highly-trained personnel equipped with specialist equipment and armament, operating under principles of self-sufficiency, stealth, speed, and close teamwork. Special Forces are sometimes considered a force multiplier, as when they train indigenous forces to fight guerrilla warfare.
The selection processes and training for Special Forces units tend to be more rigorous and than training for conventional military units. Personnel of some Special Forces units could also require much higher security clearance than regular military personnel, because they have access to sensitive or classified information.