The public domain is a range of abstract materials – commonly referred to as intellectual property – which are not owned or controlled by anyone. The term indicates that these materials are therefore "public property", and available for anyone to use for any purpose. The laws of various countries define the scope of the public domain differently, making it necessary to specify which jurisdiction's public domain is being discussed. Furthermore, the public domain can be defined in contrast to several forms of intellectual property; the public domain in contrast to copyrighted works is different from the public domain in contrast to trademarks or patented works.
Source
Wikipedia
See Also
SmallBusiness.com Glossary