From The Copyright Alliance:
The U.S. Copyright Act is a strict liability statute. In other words, following a “rule” that you believe to be true but which turns out to be a myth will not excuse you from liability for infringement. Under certain circumstances, it is possible to plead “innocent infringement,” but even that only serves to reduce the amount of damages you may owe and does not excuse your infringement.
Here are four of the most common copyright myths—debunked.
Myth #1: Public Access = Public Domain
The first myth is that anything to which the public has access, or that is publicly available, is in the public domain; i.e., if it’s on the Internet, it can be used without a license or other permission. This is far from the truth.
Contrary to popular belief, whether a book, work of art, lyrics, sound recording, or other copyrightable work is in the public domain does not depend on where the work can be found. Instead, determining if a work is in the public domain depends on when the term of copyright protection for that work expired— or if it existed in the first place.
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Myth #2: The Poor Man’s Copyright
The second myth is a “theory” that has endured for a very long time and remains surprisingly popular with freelance writers. Instead of registering the copyrights in a work with the U.S. Copyright Office, the myth is that the protection of a “poor man’s copyright” exists when an author mails himself or herself a copy of a work and then preserves the unopened envelope when he or she receives it in the mail. A variation of the theory is having the work notarized.
Mailing yourself a copy of your work or having it notarized has no legal effect. While it may serve as evidence that the work is in your possession as of the date it was mailed or notarized, it in no way proves that you are the author who created that work or holds the rights in it. The only way to register a copyright and to have documentation of your ownership in a copyrightable work is to file an application with the Copyright Office, which leads us to the next myth.
Myth #3: Registration Isn’t Necessary
Unlike the first two debunked myths, there is some element of truth to the third myth, that registration with the Copyright Office is not necessary for a work to be eligible for copyright protection. But not registering the copyright in a work would be shortsighted and not recommended for anyone wanting to be able to enforce his or her copyrights.
Under current law, registration with the Copyright Office is not required for works created after January 1, 1978.9 Provided a work is sufficiently creative and falls into certain enumerated categories, an author’s work is protected by federal copyright law as soon as it is “fixed in a tangible medium of expression.”10 Copyright protection does not cover ideas, only the expression of those ideas. In other words, telling one or more friends about your idea for the next great American novel or of a portrait you wish to paint does not guarantee any rights under U.S. copyright law. But as soon as the idea is expressed tangibly—for example, by writing the novel or painting the portrait—the work is protected by copyright law. Then, if someone copies the novel, painting, or other work of authorship without getting permission, the author can assert infringement.
An author cannot bring a lawsuit for copyright infringement, however, without a certificate of registration from the Copyright Office.
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Myth #4: The 30 Seconds/500 Copies/Two-Thirds/200 Words Rule
The final myth is that permission or a license is not needed if only a certain number of copies are made or a certain amount or percentage of the work is used, and that sticking to these arbitrary numbers automatically qualifies the unauthorized use as “fair use” under the Copyright Act.
With acknowledgments for creativity, there is no bright-line rule that making fewer than a certain number of copies or using less than a certain amount of a work somehow makes copyright infringement permissible under copyright law. Unless a use falls explicitly under one of the enumerated limitations on a copyright holder’s exclusive rights set forth in the Copyright Act,17 permission must be sought from the rights holder to reproduce, distribute, publicly perform, publicly display, and/or create derivative works of a copyrightable work—whether or not it is registered with the Copyright Office.
Link to the rest at The Copyright Alliance