What is "transformativeness"

In United States copyright law, transformativeness is a characteristic of some derivative works that makes them transcend, or place in a new light, the underlying works on which they are based. In computer- and Internet-related works, the transformative characteristic of the later work is often that it provides the public with a benefit not previously available to it, which would otherwise remain unavailable. Such transformativeness weighs heavily in a fair use analysis and may excuse what seems a clear copyright infringement from liability.