Visiting a world that doesn't exist yet can be a bit of a trick -- unless you have a good science-fiction book to power your journey. From a world defended by dragons to one where humans are enslaved by subhuman monstrosities, the only limit to science fiction is that it must be capable of existing in this Universe, more or less. Within that single condition, anything goes.
My bookshelves include a wide variety of science fiction, from many different authors, using a multitude of different settings for their stories. Classifying science fiction is largely an exercise in futility -- there are so many genres, and so many sub-genres, and so many authors who don't fit neatly into any genre, that the best I can do is create a few obvious categories and toss the rest into a giant grab-bag.
Hard-science SF is science fiction in which the emphasis is on the science.
Military stories have been a staple of fiction as long as fiction's been around. Military SF consists of military fiction set against an SF background.
Juvenile SF is just that: SF written primarily for a juvenile or teen audience.
The period from about 1930 to 1960 is known as the Golden Age of Science Fiction. It produced many good SF writes, and more than a few great ones. During the Golden Age, authors and stories went in every possible direction, exploring the limits of the known and the possible. Most of these works carry the unique flavor of the Golden Age no matter what genre they belong to, so I've grouped them all as Golden Age SF.
There are a few authors whose work I enjoy so much that they form a category of their own in my collection. Anne McCaffrey is one of these. David Weber is another.
Now we come to the grab-bag: a huge mass of books that doesn't fit any single genre, so I heap them all together as "core science fiction."
SF exists in visual media too, and sometimes those spawn written tie-ins. Novelizations of TV and movie scripts have been around as long as TV and movies have been, but in recent years a new type of tie-in has begun to proliferate: original stories based on TV series or movies. Star Trek really started this phenomenon back in the late 70s, but others have joined in, resulting in a flood of such tie-in novels. Most of them are pure junk, but a few are worth reading. My bookshelves include four major groups of tie-ins:
First, there's my collection of Star Trek books -- this was down to about twenty at last count, after I got rid of a number of them for reasons of space.
I also have a number of books based on the Star Wars saga.
On another shelf are some TV tie-ins, mostly from Babylon 5.
Finally, there are two or three books about the making of various movies and TV series, plus a handful of movie novelizations.
