What is Speculative Fiction?

I get asked this question a lot when I tell people what I do. So, for anyone who may be wondering, here it is:
Speculative fiction is, in short, fiction that is not based in or on reality. However, this concept can take many different forms, so here is a quick rundown of some of the basic genres that speculative fiction usually gets broken into.
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-Fantasy Stories of this genre are usually set in alternate universes, with little or no connection at all to Earth, its history, its laws of nature, or rules of operation. (The exception would be Historical Fantasy, which is set on Earth but usually based on fictional countries or people groups. The Princess Bride is a good example of Historical Fantasy.) Fantasy stories often involve the use of magic in some form (Click Here to read my thoughts on magic in Christian Fiction) and fantastic creatures such as dragons, fairies, elves, mermaids, etc.
-Science Fiction (sci-fi) This genre is extremely versatile, so a good rule of thumb for identifying it is the use of highly advanced technology. A sci-fi story can be based on Earth and revolve around technology developments far beyond our own, or it can be based in an alternate universe whose technology is highly developed.
-Alternate History While all fiction is essentially based on the premise of 'What if?', Alternate History takes the question to the extreme. What if the English throne had stayed in the line of King Arthur? What if it was the Russians, not the English, who colonized Australia? What if the Roman empire hadn't fallen? What might the world be like then?
-Steampunk This one is relatively new even to secular fiction, and virtually unknown to Christian fiction as of yet. The basic premise of the Steampunk genre is: What would science fiction have looked like to the Victorian Era world? Now some of you may be thinking along the lines of Jules Verne's 20,000 Leagues Under the Sea or Around the World in 80 Days. And you would be absolutely right. In my personal opinion, Steampunk could be the next big trend in fiction.
-Legend The Legend genre is pretty self-explanatory. Arthurian legend, Norse sagas, mythology, all fall under that heading.
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What is your favorite speculative genre?