When someone creates a work, he automatically has a copyright to the created product. This right can be sold or licensed; if you have been paid to create something, the person who paid you has purchased the copyright in advance.
Any work created after Jan. 1, 1978, has a copyright lasting from the date of its creation until 70 years after the author's death.
You can't be considered to have a copyright on a book until it is in tangible form such as a disk or written on paper. Under the Berne copyright convention, an international law, once the work is tangible, it has a copyright.
Under fair use, a person is allowed to use a copyrighted work without permission. Fair use includes using the work in a critique, making fun of the work or using the work to teach a class. Fair use does not give permission to simply republish the work.
Under the First Sale Doctrine, purchasing a copy of the created work does not give the owner permission to recreate it in any way, though it allows for lending, reselling and disposing of the item.
The copyright holder has exclusive rights, and if someone other than the holder tries to use these rights, he can be fined for compensation lost profits or statuary damages. If the act was committed willfully for profit, the perpetrator can be found criminally liable.