When a piece of work is in the public domain, that means that no one owns the copyright to it anymore and anyone is free to use it. Great, right?
So, how do you know whether a work is in the public domain?
The most common way that work falls into the public domain is by aging out of its copyright protection. The law sets a time limit on how long work can be protected by copyright. But those rules have also shifted over time, so it can be hard to know for sure. Here’s a helpful chart by Cornell that breaks things down.
One rule to keep in your back pocket: works published before 1923 are in the public domain.