The Public Domain is the collective of works that are not covered by intellectual property rights in any way whatsoever -- usually because the intellectual property rights have expired (or never existed), but sometimes because said intellectual property rights are forfeited (or waived) by the creator. Examples include the English language, the formulae of Newtonian physics, the works of Shakespeare and Beethoven, and the patents on powered flight. This also applies to many old movies, cartoons, novels, poems, comics, etc. In general, Public Domain works make for a great resource for those who need a quick watch or read but don't have the cash.
Since Public Domain works are not covered by copyright or other IP rights, they can be used as the basis for -- or part of -- new creative works without fear of running into lawsuits or other legal issues. Shakespeare's works, for example, have been adapted into numerous films with their own unique spin on The Bard's tales.
In general, works enter the public domain by one of three means - the copyright lapses due to age (70 years after the death of the creator, or 120 years after creation/95 years after publication (whichever is less) for works where a corporate entity is the creator, being the current legal standard), by the holder waiving his/her/its copyright, or (pre-1977) due to the creator not actively applying for and renewing it. (After 1977, copyright became automatic as soon as a work was written down or recorded, and this standard was applied retroactively to any work not yet in the public domain.) In the U.S., it is generally accepted that any work produced prior to 1923 is public domain, whereas works produced thereafter may or may not be under copyright owing to a litany of circumstances. For certain works, this is a muddy issue especially as pertains international laws and treaties - the King James Bible, for instance, is considered public domain in the U.S., while in the U.K. it is held to be under perpetual copyright by the Crown, and in Germany the government has claimed perpetual copyright over Mein Kampf in order to prevent it being openly published and distributed there.
Up until recently, it was commonly accepted that once a work entered the public domain it stayed there, barring extraordinary circumstances. However, as of January 2012 it became possible in the United States for works to be taken back out of the public domain. Do not be surprised if some works stop being public domain should a corporation find sufficient
revenue reason for doing so.
Here on All The Tropes, the Public Domain comes into play via four different tropes:
- Public Domain Animation: Cartoon short subjects that are in the public domain.
- Public Domain Feature Films: This covers public domain feature length movies like The Birth of a Nation and Night of the Living Dead.
- Public Domain Stories: This includes folklore, short stories, poems and novels that are in the public domain.