In short, public domain images are not restricted by copyright and do not require a license to be used in your projects. A public domain status allows users unrestricted access and unlimited transformation and without permission. It literally says that the public owns it, so public domain status allows the user unrestricted access and unlimited creativity

While this may sound simple enough, one of the most complicated issues is how to identify what is considered public domain, and for that purpose it’s vital to take into consideration that the copyright laws are different in every country. On this post we will consider the case of the United States alone.

Factors that define a public domain status for works created in the US?

When was it published?: if you know when something was publish then you can identify if it’s public domain or not. Remember this basic rule: any work (books, images, songs, movies, artwork, etc.) published in the United States before 1923 is considered public domain. For works published in the United States after 1923, many factor will depend whether they could be considered public domain:

Give away: sometimes owners actually give away their work to the public by relinquishing copyright protection.
Produced by the government: anything produced by the government is public domain, this includes anything made by an employee or officer of the federal government as part of that person’s official job.
1989 automatic right: anything produced after 1989 is automatically protected so the copyright is an automatic right, this means that the author doesn’t have to file any paperwork.

Before 1989: there are cases where work that was published in the USA before 1989 but without copyright filed by the authors ended up considered public domain. Back then the paperwork was a requirement.

Not renewed copyrights: Renewal was a requirement for works published before 1978. So anything published in the USA before 1964 where copyrights were not renewed, are consider to be public domain.