Copyright duration differs between countries, lasting between 50 and 100 years after the author's death, or for a shorter period for anonymous or corporate authorship. Thereafter, the copyrights of a work expire and the work becomes part of what is known as the 'public domain'.

In the public domain, works are not copyrighted and are therefore freely available. Works that are in the public domain can be accessed and used freely and for any purpose - e.g. printed, copied, displayed, distributed, performed, modified or sold - without a licence.