Question

What is the best explanation of what “public domain” means?

“Public domain” means a text or an image is free for anyone to use.
“Public domain” means everyone is familiar with an image.
“Public domain” means an image is beloved by almost everyone.
“Public domain” means many people have created similar images.

Answer 1

A. “Public domain” means a text or an image is free for anyone to use.

Answer 2

A.  Public domain means whose exclusive intellectual rights have expired , have been forfeited, have been expressly waived, or are incapable.  So if someone owned a building but had their rights for the building terminated, that building is now a public domain until someone buys the building. So, after the building has been handed over because of the terminated rights of the owner, it is now a "Public Domain".