What is meant by Public Domain?
Simply put, creative works become the public domain (or in other words, belonging to and available for use by the public) once the intellectual property rights to the works have expired.
So what is meant by expiration?
It depends on the laws of the specific country. In the New Zealand, for example, copyright for a song expires 50 years after the end of the calendar year in which the last surviving writer or composer has passed away. The expiration term is different for sound recordings, publications, film and broadcast. In the US, it’s even more complicated and in other countries around the world, the language defining public domain is quite specific and the time defined for works to enter the public domain vary greatly.
What type of creative works can become public domain?
For the most part, sound recordings, publications, film or broadcast are pertinent for this discussion, but software or even tangos may enter the public domain in different countries. Once a creative work enters the Public Domain, it may be freely adapted, arranged and translated and new copyrights may even be claimed.