According the U.S. Copyright Office's Factsheet on Fair Use, the rights of copyright owners are subject to limitations. One of the more important limitations is the doctrine of "Fair Use."
The doctrine of Fair Use allows users of copyrighted works to reproduce and reuse copyrighted works in ways that are considered fair--such as criticism, comment, news reporting, teaching, scholarship, and research.
Section 107 of U.S. Copyright Law provides four factors to consider when considering whether the use of copyrighted works is a fair one:
Transformative use is a relatively new addition to fair use law, having been first raised in a Supreme Court decision in 1994 (Campbell v. Acuff-Rose Music). A new work based on an old one work is transformative if it uses the source work in completely new or unexpected ways.
In other words, does the new work have a different purpose than the original work? And, is the amount of the original work used appropriate for this new purpose? If the answer is "yes" to these two questions, there would be a strong case for fair use.
Importantly, a work may be transformative, and thus a fair use, even when all four of the statutory factors would traditionally weigh against fair use.
Parody is one of the most clearly identified transformative uses, but any use of a source work that criticizes or comments on the source may be transformative in similar ways.
Courts have also sometimes found copies made as part of the production of new technologies to be transformative uses. One very concrete example has to do with image search engines: search companies make copies of images to make them searchable, and show those copies to people as part of the search results. Courts found that small thumbnail images were a transformative use because the copies were being made for the transformative purpose of search indexing, rather than simple viewing.
Transformative use is a relatively new part of copyright law and still developing.
The Codes of Fair Use Best Practices, from the Center of Media & Social Impact, describe ways of using fair use in a variety of common contexts, including filmmaking, dance, poetry, journalism, visual arts, academic research and teaching.
Taking a photograph of a copyrighted item can sometimes count as reproducing the item and is a violation of copyright. However, there are some cases when it is okay - read this document from the World Intellectual Property Organization to learn more.
Images from the Association for Research Libraries.