Works put on the Internet are considered "published" and therefore qualify for copyright protection. A work put on the Internet is not considered public domain simply because it was posted on the Internet and free for anyone to download and copy.
The best way to enforce Internet copyright is through the Digital Millennium Copyright Act.
The Digital Millennium Copyright Act of 1998 is designed primarily to limit the liability of Internet service providers for acts of copyright infringement by customers who are using the providers' systems or networks.
The DMCA was enacted both to preserve copyright enforcement on the Internet and to provide immunity to service providers from copyright infringement liability for passive, automatic actions in which a service provider's system engages through a technological process initiated by another without the knowledge of the service provider.
To protect your rights under the DMCA, you should write a DMCA letter to the infringing personís Internet Service Provider and the major search engines, such as google at www.google.com/dmca.html
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