Manufacturers, publishers and other copyright holders have developed access technologies that limit usage or reproduction of digital content and devices. The Digital Millennium Copyright Act criminalizes other technologies, devices or services that are intended to circumvent this control and access to copyrighted works.
Intellectual property is the term for a broad category of creative properties. This includes copyrights, patents, and trademarks. Copyright applies to creative endeavors that such as literature, art, music and other creative works such as films, sound recordings, photography, and architecture. Patents cover inventions, processes and item design. Trademarks are designs, embalms, logos, etc. that identify a product or its manufacturer.
This term referrers to works that it is difficult or impossible to identify or contact the copyright holder. How can this happen? The work might have been published anonymously, or was not published at all (diaries or letters for example). The owner of the copyright may not be aware of his or her ownership. The copyright owner may have died, or, in the case of a company, gone out of business. However, orphan works are not public domain.
Public domain referrers to works that are no longer covered by intellectual property right laws - works which the patents, copyrights or trademarks have expired. For example, the works of Shakespeare are in the public domain. In the United States, works published before 1923 are in public domain because the length of copyright has expired.
“Works for hire” is a special class of copyrightable works where the person who actually created the work is not the copyright holder or the legal author. For example, a company that does research and development might require an employee to write a technical manual. The employee wrote the manual, but the company owns the copyright. The manual would be considered a “work for hire”.