Copyright stuff
"BTW, I've read some posts and it seems many people have a misconception about a copyright. Once you have put your story into a tangible form, (meaning onto a computer screen, on paper, whatever) it is copyrighted to you. If a publisher likes your book well enough to publish it, he'll copyright it (meaning officially) for you. They want you to write more to make money for them. You can always copyright your own work to you (officially) by sending to Washington. It costs about 20-30 bucks. How writers lose out on money has more to do with the contract they sign about the book, not the copyright."
I used to work in publishing, kaiscomet is pretty much right about this stuff. The "official" copyright (sending it and getting it registered by the US Copyright office) is really more about providing a date on an official government record for the creation of your written product/story/what have you. It's basically an insurance policy in case some time in the future there is a question of authorship, of who actually wrote something (which almost never happens). In film (I also worked in that biz) screenwriters have the Writers Guild which does essentially the same thing (registers written creative material), but also provides legal defense for its members and/or arbitration for authorship disputes (which seems to be a more frequent problem in film...seazy biz, that's partly why I left).
When a writer writes something, they own the characters, setting, etc. Their creation is essentially their property and their potential annuity in the future (and that of their heirs for 75 years after their death!). Sometimes a writer will sell away the rights to their setting, characters, etc. (hopefully for good money). This is what often happens in Hollywood, a studio or producer will buy the property forever, it becomes theirs to do with what they will and rights to characters, setting, etc. become theirs. Sometimes they merely option a property, this means they take posession of the rights for limited amount of time (one or two years is common) in which to get a movie made of the project. If they do get it made, they then own the property outright, usually (and the writer hopefully gets more compensation on the "back end"). If a movie doesn't get made in that time period, the rights revert back to the screenwriter and he gets to try an sell or option it again, if he can.
Publishers don't normally buy the rights to a story from authors, they just buy the right to put the property into the market. The right to sell a story to Hollywood, to toy companies, what have you, usually remains with the writer (though anything can be negotiated in a contract and sometimes is).
Things get a little more complicated when someone writes a novel for D&D, Star Trek or Star Wars, etc. In those cases, a person has really just been hired to write stories for characters, settings, etc. that were created by someone else previously - the author doesn't own those characters and it probably says so in any contract they sign with whoever is hiring them. In this case the copyright of the original creator takes presedence over the creation of the later author.