--from the Oxford English Dictionary, 2nd ed.: The exclusive right given by law for a certain term of years to an author, composer, designer, etc. (or his assignee), to print, publish, and sell copies of his original work.
Copyright is most often thought of today in terms of restrictions, but it is also meant to stimulate new knowledge and creativity by allowing creators to benefit from their work.
--from the United State Copyright Office Circular 1, Copyright Basics: Copyright is a form of protection provided by the laws of the United States to the authors of “original works of authorship,” including literary, dramatic, musical, artistic, and
certain other intellectual works. This protection is available to both published and unpublished works. Section 106 of the 1976 Copyright Act generally gives the owner of copyright the exclusive right to do and to authorize others to do the following:
To reproduce the work in copies or phonorecords;
To prepare derivative works based upon the work;
To distribute copies or phonorecords of the work to the public by sale or other transfer of ownership, or by rental, lease, or lending;
To perform the work publicly, in the case of literary, musical, dramatic, and choreographic works, pantomimes, and motion pictures and other audiovisual works;
To display the work publicly, in the case of literary, musical, dramatic, and choreographic works, pantomimes, and pictorial, graphic, or sculptural works, including the individual images of a motion picture or other audiovisual work; and
In the case of sound recordings,* to perform the work publicly by means of a digital audio transmission.