Copyright law is complicated and there are a lot of misunderstandings about it. These are a few of the most common:
1) "I can secure my copyright by mailing a copy of my work to myself."
WRONG: Mailing a copy of your work to yourself is a waste of postage. You generally own the copyright to your work at the moment of its creation. However, in order to maximize the legal rights to your copyright, you must register it with the United States Copyright Office in a timely manner.
2) "I found a photograph on the Internet, so it’s in the public domain and I can make use of it."
WRONG: Just because something is on the Internet, that does not mean it’s in the public domain and therefore free for anyone to use. Quite to the contrary, most of the content on the Internet is protected by copyright law. Two major exceptions are: a) materials covered by a Creative Commons license, where the creator of the work has waived all or some of his copyright protections; b) older works—generally works created before 1923. The fair use doctrine also permits unauthorized use of copyrighted works, but its application is quite fact-specific and requires careful legal analysis.
3) "I bought a piece of art, so I can reproduce it as I please."
WRONG: Just because you bought a physical object (i.e., a piece of art), that does not make you the owner of the copyright to that physical object. You may own the property right in the actual art, but the creator of the work likely still owns the intellectual property (i.e., copyright) in that work. For example, when you buy the latest U2 album, you may own the physical object in comes on (a CD, for instance); but, you do not own the copyright to the U2 album. Thus, you may not reproduce it as you please.
4) "I registered my screenplay with the Writers Guild so I have full copyright protection."
WRONG: Although there may be some utility to registering a work with the Writers Guild, the only way to maximize the legal rights to your copyrighted work is to register it with the United States Copyright Office.
5) "I sampled a three second riff from an old James Brown song on my new album. Since it’s not the whole song, I’m in the clear."
WRONG: Even a small use of someone else’s copyrighted work,
such as a song, can give rise to massive copyright liability if it is done without
permission. That said, certain unauthorized uses (such as a short quotation
from a novel in a book review) can constitute fair use. Consult a copyright
attorney for further information.
6) "Someone paid me to create a work for them. They therefore own
the copyright."
WRONG. Ownership of copyright in such situations is a complicated
issue and depends on a variety of factors, including the nature of the relationship
between the creating and paying parties, the type of work at issue and the existence
of a written special commission agreement.