Warmatrix

Special forces are elite troops, trained for 'special' operations, practicing 'unconventional' warfare. The dividing line between regular and special forces is vague. Skirmishers, raiders and assault troops occupy a middle ground between the two. On the other side of the spectrum, the distinction between special forces and spies, assassins and other non-military personnel is often blurred too.
Scouts, spies, infiltrators, saboteurs and other special troops have been used since ancient times. Some examples are the Seleucid "epilektoi"; the Japanese "shinobi"; rangers in the American Civil War; Ghurka scouts. During World War II several countries started experimenting with training units of special forces. The leader in the field was Britain, which established the Special Service Brigade that later developed into the commandos. The first British commando units were used to mount raids on German-held harbors and strongpoints, to force the German army to keep large garrisons in the west. At first these operations were, though brave, very amateuristic and opportunistic, leading to large numbers of casualties. Later they became more efficient and effective.
Several countries copied the idea and established US Rangers, Italian ADRA, Russian Spetsnaz and others. After the world war, the concept really took off; almost every military force established their own special forces units. Their specialization, level and exclusiveness was raised even higher than that of the commandos. Common to all special forces is that selection standards are high, including physical fitness, psychological stability and intelligence. Intense training adds skills to the basis, creating soldiers of above average ability. The standards, combined with the high cost of training, keeps the numbers within the special forces small, further strengthening their elite status.
Modern special forces engage in a variety of tasks, including things like conducting reconnaissance and sabotage missions, often behind enemy lines; performing assaults; rescuing hostages and stranded soldiers; rapidly responding to crises; defending against chemical, biological and nuclear weapons; training other troops; fighting guerrillas and terrorists; performing assassinations. Some of these are offensive, others defensive. Many are secretive, some even clandestine. Some rich countries can afford to train specialized units; others set up special forces that must be jacks-of-all-trades.
Special troops are well qualified for the special operations that they have trained for, but cannot replace the regular troops in conventional, large-scale warfare. Rather, the two complement each other. Though as the proportion of unconventional warfare is rising, the importance of special forces is increasing also.