The first flight was in 1974 and at the time represented a revolutionary design because it was the first "fly by wire" aircraft. It would use electric signals to control the aircraft instead of hydraulics. As a result, it is one of the more nimble aircraft in the world.
It entered active duty in 1978. It is also used by 25 other countries.
It is capable of supersonic flight.
The F-16 has gone through a number of upgrades since it's first flight. It is currently at the "E" level.
Eventually the F-16 Fighting Falcon will be replaced by the F-35 Lightning II which is currently in development.