Fighter aircraft
A fighter aircraft generally is a fast and maneuverable aircraft, whose capabilities include attacking other aircraft. There are a variety of missions, and many fighters are best at one but can do others. A few multirole fighters truly do all jobs well, although a specialized aircrat may be superior for a specific mission.
Jet-propelled fighters are classed in "generations".
Fighter missions
Within a given generation, there may be specific fighters optimized for a particular mission.
Air superiority fighter
Optimized for engaging and destroying other fighter aircraft, often at long range. While it was limited to gun range, the F-86 Saber was one such aircraft, while the F-15 Eagle is an advanced air superiority fighter, allegedly developed with the motto "not a pound for air to ground" (see F-15E Strike Eagle)
Interceptor
Interceptors may be short- or long-range. Short-ranged interceptors, such as the MiG-21, protect relatively small areas. Long-range interceptors, such as the MiG-25 or F-102 often are optimized for destroying enemy bombers far from their target. Interceptors are purely defensive (i.e., defensive counter-air), while air superiority fighters can be offensive or defensive.
Fighter-bomber
This type is optimized for attacking ground targets. Depending on the specific type, it may have relatively more or less ability to engage in air-to-air combat. Some aircraft designated as "fighters" have no air-to-air capability, such as the F-117 Nighthawk, which is really a light bomber. Other fighter-bombers, such as the F-105, do have some air combat capability, but generally would concentrate on the attack mission, perhaps relying on speed to avoid interceptors.
Multirole fighter
While almost all fighters have, at one time, been used in both ground attack and air-to-air combat, a true multirole fighter does both well. Historically, when a reasonably versatile fighter-bomber such as the F-4 Phantom II met other fighters, it jettisoned its bombload to gain maneuvering performance. Forcing the aircraft to jettison its bombs far from the target defeated its primary mission.
More recent aircraft, however, have demonstrated true multirole capability. In 1991, during Operation Desert Storm, U.S. Navy F-18 Hornet aircraft, assigned to attack a ground target, were intercepted by Iraqi fighters. Without jettisoning their bombload, the Hornets shot down the other aircraft, and completed their attack mission. The F-15E Strike Eagle also can perform at this level.
Fighter generations
The idea of a fighter generation is useful only for approximate comparison of fighters.
First-generation
The first generation of jet fighters were subsonic, armed with machine guns or autocannon for air-to-air combat, and had limited electronics. While there were earlier models, such as the Second World War German Me-262 and British Meteor, the most common examples are the Korean War-vintage U.S. F-86 and Soviet Mig-15.
Second generation
Typified by the Soviet MiG-19 and U.S. F-100, these were the first supersonic fighters, typically with limited onboard radar, and both guns and early air-to-air missiles (e.g., AIM-9 Sidewinder).
Third generation
In this generation were the first serious attempts at multirole capability, such as the F-4 Phantom II, originally developed by the U.S. Navy but operated by a large number of countries. An early Soviet design with multirole capability was the MiG-23.
Fourth generation
Fighters of this vintage had major advances in electronics and missiles. While each previous generation had been faster than the one before it, fourth generation fighters emphasized maneuverability, missiles that could attack from any angle, and long range. Soviet fighters of this generation include the Su-27 and MiG-29. U.S. equivalents split into "high-end" and "low-end", the high end, such as the F-15 Eagle initially optimized for air superiority, and the low-end, such as the F-16 Fighting Falcon, as multirole.
Generation 4.5
Several aircraft have significantly advanced electronics, maneuverability, or other features when compared to the basic fourth generation. Examples include the French Rafale and the U.S. F-18 Super Hornet.
Fifth generation
Aircraft of the current generation are more revolutionary than evolutionary, the example most often cited being the U.S. F-22 Raptor. They have low observability (i.e., stealth), supercruise, extremely advanced electronics including radars with no moving parts and low probability of intercept, and may have supercruise, the ability to fly at supersonic speed without an afterburner. The U.S. F-35 Lightning II does not have supercruise, but is better at ground attack than the F-22, and also has short-takeoff versions. Russian technology here is emerging, but the Su-47 may be of this generation.