Often, science fiction films are purely speculative in nature and are peppered with recurring themes involving science and technology. Other prevalent themes in sci-fi movies are mysticism, magic, the occult and the supernatural, which are also key elements of fantasy or occult/religious movies. In fact, quite a number of films blur the line between these genre, such as Forbidden Planet, Chronicles of Riddick, and the Star Wars series.

It's hard to define precisely what makes a science fiction film because the genre has no universally accepted definition. In fact, science fiction may vary from viewer to viewer in that what is sci-fi to me may be fantasy or horror to you.

If you've been a long-time fan of Hollywood, then you know that science fiction has come a long way. There was a time when special effects meant putting a toy spaceship at the end of a string and waving it in front of a camera or having someone dress up as an orangutan and terrorizing an entire city. Certainly, the special effects in science fiction movies have evolved from the downright laughable to today's breath-taking and awe-inspiring treatments that seem truly realistic. Some of the great milestones in this regard are marked by films such as 2001: A Space Odyssey, the Star Wars films, Star Trek: The Motion Picture and The Matrix.

Of course, science fiction films just seem to be getting better by the year, as evidenced by such recent hits as "Lord of the Rings", "I, Robot" and "Superman Returns."