Copyrights, like patents, are a creature of federal law. A copyright is the exclusive right to make, publish, distribute and publicly perform or display copies of original works of authorship, and to create other works "derived" from such works. . Copyright does NOT protect the underlying ideas, processes, procedures, methods of operation, conception or principles embodied in the copyrighted works. In some instances, these may be better protected as (hyperlink) trade secrets. Consequently, others may copy your ideas without infringing your copyrights by creating an independent expression of the idea. (expand this with explanation of originality, etc. and hyperlink)

The copyright statute also provides “consumer” exceptions to otherwise illegal copyright infringement. The duplication of a musical recording for personal use, the videotaping of a televised program or modifications to software to enable its use with hardware are some examples of these exceptions. That these activities are exempted from prosecution does not mean that they are not copyright infringement.

The law also provides exceptions to copyright infringement for the reproduction of insubstantial portions of original works for legitimate or fair use. Photocopying or quoting part of a writing for illustrative or educational purposes, downloading or copying material from a website or incorporating part of an original work in your own work out of necessity for compatibility purposes are examples of such fair use. The courts look to a number of factors in weighing the “fair use” of the work, including (1) whether the infringement is undertaken for commercial profit or for the purpose of criticism, commentary or education, (2) whether the use is “transformative”, evolving the original or engaging in pure duplication, (3) whether the use impacts an existing or likely market for the original work, (4) the availability of the original work, (5) whether only so much of the original as necessary is copied, (6) industry practice and (7) whether the copy was undertaken in the good faith belief that the use was fair or constitutes a knowing infringement in another’s copyrights. With the digitization of copy protected works, the ability of consumers to error on the wrong side of “fair use” has prompted Congress to pass the Digital Millennium Copyright Act (DMCA). The result is emerging security measures and technology, amounting to “digital locks” on consumer goods such as DVD movies, CD music and computer software, preventing the casual copying traditionally enjoyed, and sanctioned, by the copyright statute.

Filing a copyright registration is not a requirement of copyright protection. Copyright protects unauthorized reproduction of all works that meet the requisite elements of originality and reduction to a tangible medium. Nevertheless, registration of copyright is relatively inexpensive and offers many advantages to the copyright holder. First, in an instance of infringement, a copyright registration, or at least evidence of having filed an application for copyright is required before the copyright owner may proceed to sue the infringer in federal court. Early filing of registration also favors the copyright holder who finds themselves in court. For the relatively nominal registration fee, the early registrant is afforded a presumption of copyright validity, the option of electing statutory damages and may be awarded attorneys fees against the infringer. Given the advantages, there is no excuse not to register any work having commercial value.

Compared to patents, having a life of 17 or 20 years, copyrights have a long life. In the case of natural persons (as compared with corporate registrants) copy­rights last for that person's life plus 50 years. Sometimes, the estates make more money than the original author. Elvis Presley’s estate is reputed to make more than “The King” ever did. “Works made for hire", created by an employee but registered in the name of the employer, the U.S. copy­rights last for the lesser of 100 years or 75 years from the date the work is first published.

Copyright, like other types of personal property, is subject to assignment and licensing. Perhaps the most recognizable copyright license is the End User License Agreement (EULA) accompanying your software. Even non-commercial software, such as freeware or public domain software (GNU) is copyright protected and is subject to use consistent with the author’s grant of license. The license exists, and limits the end users rights, even where the software is provided without charge. Owners can license less than all of their rights under copyright law. Your EULA licenses your use of the object code software but probably prohibits copies (except one for archival purposes) and further prohibits the disassembly or modification (“reverse-engineering”) of the software. To assist in protecting investments in software development, the “rule of doubt” allows the registration of less than a complete copy of the software code, facilitating its continued protection under (hyperlink) trade secret laws. Absent this “rule of doubt”, any work submitted for copyright registration is subject to public scrutiny, voiding any trade secret protections that otherwise existed. A software license may also limit use to certain computer systems in which the software is first installed or to a particular site, and can prohibit transfer, resale or sublease of the software. These same limitations may apply to any other type of copyright work, including written works, performance works, compilations in a medium or even your own website.