F-35 = JSF = joint strike fighter.
This fighter is a low cost alternative to the F-22. Joint strike
means it is designed to be used by all branches of the military
(Airforce, Navy, and marines) and will be used by many foreign
countries. It will be replacing the F-15, F-16, and the
harrier.
It has vertical takeoff landing capability like the harrier. It
will be produced in larger numbers than any other jet fighter and
may be the last manned fighter the USA ever builds. The future of
fighters is unmanned due to limitations of speed and
manueverability of having a pilot on board.