Fighter jets emerged in the late and post WWII era as a faster way to get from A to B, destroy C and get back to A alive. During that war, however, a rare fighter jet and a common propeller fighter would be incompatible for combat do to the speed difference. Primitive bombing aiming systems made it nearly impossible for jet fighters' use as bombers at that time as well.
During the Cold War, fighters would come to shine as yet another power joust between the USA and USSR. Every new US fighter would be matched (or attempted to be matched) by the USSR and vice versa. Bigger faster jets were being invented and produced one after another, with little thought to practicality. For instance, a new American fighter jet such as the F-15 Eagle would be hurried to be matched by the USSR's MiG-31 Foxhound, but the Foxhound would be all speed and no maneuverability, with a fuel tank drainable after a very short time. During the Vietnam War and similar conflicts during the Cold War, new MiGs would fall into the hands of the North Vietnamese Air Force and see combat with American planes, but under another flag. The Americans would add some F-4 Phantoms to their F-5 Tigers in order to compete with the Soviet MiG-17 Fresco and MiG-21 Fishbed.
In the seventies and eighties, the fighter scene was all about reconnaissance and interception. How quickly can we go in and take pictures and leave without being seen? And the countering motive: How can we intercept these spy planes and arrest the pilot for questioning?
Some planes for this era include the now-retired carrier based F-14 Tomcat and its still-used, versatile cousin the F-18 Hornet (Canada uses only these). For the USSR, the MiG-29 Fulcrum would hope to compete with both of these planes as well as the F-15 series. Representing this era is the American F-16 Fighting Falcon, which is very suited to escorting and dogfighting if necessary. These planes would live to be the stars of the Gulf War, leaving little work for the ground forces to complain about. (All the collateral damage is already done, boys).
When the fun and games of aerial espionage and counter-aerial espionage are over for the day, however, the darker question still remains: How can we stop the nuclear missiles before they get to our cities?
In response to this, such planes as the F-15 Eagle and MiG-31 Foxhound were produced, as well as numerous Russian designs that hardly came to fruition before the USSR collapse: the SU-27 Flanker, SU-33 Flanker-D, SU-37 Super Flanker, and the pivotal forward-swept winged SU-47 Berkut. These planes were designed in the hopes of catching up to a missile and shooting it down before it reaches the target or leaves the atmosphere. Unfortunately, all advancements would come just short of this capability, making such a feat of aviation a near-impossibility.
Presently, the USSR has generally withdrawn from the fighter universe, and European countries have filled the gap (i.e. The Eurofighter Typhoon). Overall, however, the USA commands the skies with their old F-15, F-16, F-18, as well as the coveted F-117 Stealth Fighter and the shiny computerized F-22 Raptor. The world awaits the F-22's little brother, the F-35 Lightning, but despite these advances of the single-man fighter jet, the military aviation world eagerly awaits advances in unmanned drone technology.
The twentieth century was the era of men fighting in the sky. This new century will see flying, fighting robots and (has already seen) alternate methods of warfare, in which the enemy is too poor to afford a fighter jet and feels perfectly content and capable to get their way from their mountain cave with a warm, environmentally-friendly AK-47 under their arm and the promise of divine reward.