The purpose of copyright registration is to place on record a verifiable account of the date and content of the work in question, so that in the event of a legal claim, or case of infringement or plagiarism, the copyright owner can produce a copy of the work from an official government source.
The pre-1978 indices to the copyright records are available for public inspection at the Library of Congress.
Copyright infringement is the use of works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the copyright holder, such as the right to reproduce, distribute, display or perform the protected work, or to make derivative works. The copyright holder is typically the work's creator, or a publisher or other business to whom copyright has been assigned. Copyright holders routinely invoke legal and technological measures to prevent and penalize copyright infringement.
An advertisement for copyright and patent preparation services from 1906, when copyright registration formalities were still required in the US
Pirated edition of German philosopher Alfred Schmidt (Amsterdam, c. 1970)
Demonstration in Sweden in support of file sharing, 2006
