Free material can be copyrighted. The concept of fair use allows limited portions of a work, such as quotes, to be used for purposes like commentary, criticism, news reporting, and scholarly reports. There are no specific legal rules regarding the amount of material that can be used, but four practical questions can help determine if the use of someone else's work might qualify as fair use. These questions consider whether the new work is transformative, the nature of the copyrighted work, the amount and substantiality of the portion used, and the effect of the use on the potential market for or value of the copyrighted work. While public domain material is free of centralized control, it can still be subject to license terms, even if it is available for free online.