A copyright is automatic. Once something original is created, even if it's a poem jotted on the back of a napkin, that creative work belongs to its owner. The copyright notice just eliminates any doubts of ownership, especially in court.
"Copy from one, it's plagiarism; copy from two, it's research," joked writer Wilson Mizner.
Published or unpublished, creative work belongs to the person who created it. Exclusively. These rights include reproduction, distribution, and adaptations.
The Federal Copyright Act of 1976 protected ownership and The Sonny Bono Copyright Extension Act of 1989 extended the period of protection. How long does a copyright last? Good question. The explanation is complicated, but here's a part of the answer:
Work published in the U.S. before 1923 is in the public domain.
Work published with copyright notice between 1923 and the end of 1963 is protected for 28 years with a renewal for 47 years. That has now been extended by 20 years, for a total renewal of 67 years. If the work has not be renewed, it is now in the public domain.
Work published with copyright notice between Jan. 1, 1964-Jan. 1, 1978, is covered for twenty-eight years for the first term, with an automatic extension of 67 years for the second term.
Work created, not published, before Jan 1, 1978, is protected for the life of the author plus 70 years or Dec. 31, 2002, whichever date is longer.
Work published or created after Jan. 1, 1978 is protected for the life of the author plus 70 years.
For more information, check out nolo.com or findlaw.com. Or go straight to the source, the U.S. Copyright Office.
As far as originality goes, French writer Francois Chateaubriand once said, "An original writer is not one who imitates nobody, but one whom nobody can imitate." Moby Dick creator Herman Melville put it nicely, too: "It is better to fail in originality than to succeed in imitation."
Give credit when it's due.