The nearly insatiable demand of consumers for books, movies, music, and software has led to increasing copyright infringement, estimated to cost copyright owners more than $20 billion each year. Copyright infringement occurs when a work derives from another and shows substantial similarity to the first work. Infringement does not require intent. Even an innocent use can be infringement. There are a variety of defenses to infringement, chief among them that of fair use, meaning a use for scholarship, educational, or news reporting purposes, or as a parody. Remedies include damages, injunctive relief, and seizure of the infringing goods.
Infringement occurs when one or more of the exclusive rights granted to copyright owners (reproduction, adaptation, distribution, performance, or display) is violated, whether the violation occurs innocently or with intent. Because two identical works can coexist as long as they were independently created, the accused work must derive from the copyrighted work for infringement to exist. Even if two works are identical in every respect, if they were independently created, there can be no infringement.
Because it is difficult to find direct evidence that a work has been infringed (there are seldom witnesses who have observed any copying),