Star Wars is an extremely popular Sci-Fi saga. Initially containing an Original Trilogy of three movies (now known as Episodes IV, V, and VI), over the following 40 years it has come to include 4 additional live action movies, a CGI movie, one animated cartoon, two CGI cartoons, a Christmas Special (Seriously), a few hundred video games, and 80 bajillion books.
If you ask a Star Wars Fan, 90% of this is crap, but thankfully most of it isn't canon anymore as of the 2013 acquisition of the Star Wars franchise by Disney. (Did a shiver just run down anyone else's spine?)
The fame of Star Wars is eclipsed only by the fanboy outcry against the degree to which George Lucas pissed on his own legacy. The Original Trilogy followed the archetypal quest pattern (leading some people to consider it closer to fantasy than science fiction); then twenty years later, George thought it would be a smashing idea to 'expand' the universe with a host of improvements that eroded the mystique of the original story.