LibAnswers

According to United States Copyright Law, a work is protected by copyright for a certain amount of time before it falls into the Public Domain.  Once in the public domain, it can be used freely, that is, without permission from its creator. 

It can be tricky to tell when a work becomes public domain, as the time period depends on the type of work.  For more information, see the chart created by Peter B. Hirtle at the Cornell Copyright Information Center (http://copyright.cornell.edu/resources/publicdomain.cfm).  The JCC Libraries also have a Copyright LibGuide available (http://sunyjcc.libguides.com/copyright).