What is "copyscape"

Copyscape is an online plagiarism detection service that checks whether similar text content appears elsewhere on the web. It was launched in 2004 by Indigo Stream Technologies, Ltd.

Copyscape is used by content owners to detect cases of "content theft", in which content is copied without permission from one site to another. It is also used by content publishers to detect cases of content fraud, in which old content is repackaged and sold as new original content.