Originally released as Star Wars, this film started a cult trilogy of space opera, and later a trilogy of prequel episodes that were generally and rightly considered to be far inferior to the original series.
Set a long time ago in a galaxy far away, the film marries sci-fi and fantasy with panache. The Rebel Alliance struggles to destroy the evil Galactic Empire’s super-weapon, the Death Star. But farm boy Luke Skywalker must first become a hero warrior. Other memorable characters included the (an)droids R2-D2 and C-3PO, Han Solo (Harrison Ford’s big break), Princess Leia, the furry Chewbacca and Obi-Wan (played with welcome gravitas by Alec Guiness). James Earl Jones provided the unforgettable voice of the masked villain Darth Vader.
Drawing on many influences, from Flash Gordon to Akira Kurosawa as well as Joseph Campbell's theories of cultural myth-making, Lucas wrote, directed and produced the film which is noted for its special effects, massive success, and lasting influence.
FYI: The film was re-released as "Star Wars: Episode IV - A New Hope" in 1981 with new visual and audio effects which were in the main impressive, but also with several pointlessly mangled story elements including revised character motivations and scenes.