First generation

with a jet engine
built in 1940s and 1950s
The two fighter jets to see combat in World War II were the German Messerschmitt Me 262 and Great Britain's Gloster Meteor.
had straight wings and basic avionics with no radars or self-protection countermeasures.
armed with machine guns and unguided bombs and rockets
subsonic - speed less than the speed of sound

Second generation

super sonic speeds
swept wings
built in 1950s and to early 1960s
The Korean War of 1950-53 was a major catalyst for fighter jet development.
Later second-generation fighters saw the introduction of the first air-to-air radars as well as infrared and semi-active guided missiles
raar warning receivers
first development of interceptor-type aircraft while high speeds made guns unsuitable.