Here are some useful sources to understand what all can be protected by copyright laws, and what copyright is about:

• Copyright rules by subject matter explained at Wikimedia Commons. And the same in French.
• Intellectual property wiki

People often take the copyright lightly, ignores it, or simply don't know it very well. We easily refer to fair use, which more or less covers only cases in United States, but should not be stretched to cover publications globally shared on Internet.

Here's one case. If I record a lecture, and decide to publish it, it is okay as long as I do not show someone else's art or design on that video. But if I for example show a book cover on the video, saying it is a book everyone should read, I then very likely breach the copyright by "accidentally" showing the copyright protected cover art. Therefore I should for example blur out the book cover before publishing the video. Unless, the lecture is about that cover art illustration and artist who made it.

So, we may think it is alright to share some wonderful art made by famous artists, reproduced for example with camera. However, that is still a copyright infringement. No matter how good and sincere our intents would be. No matter how detailed information we would give to explain who's work there becomes represented. We still should ask the permission for the publication, from the artist her/himself, or from the current living and legal copyright owner.

And I think also I have several questionable images here at Ipernity. For example some of my shots showing statues are probably copyright infringements against Finnish copyright law. It is not a problem if the statue is shown on the background, and the statue is not the clear main subject on the photograph. But if the main subject is more or less the statue itself, then the image very likely infringes copyright at least here in Finland.

Meaning, we all may have some "skeletons in the closet". And probably I need to go through my old published photos ...

However, I ask one thing from all of you. Please don't take the role of inquisitor to your hands, and furiously start to report each and every case you find. Try to see the big picture. And first clean your own closet. It is alright to report clear and so called blatant cases. And if you first decide to contact the person you suspect, please do it in very polite manner. The person you approach may not even know s/he has done something wrong. And the very best thing you can do is to share the knowledge and information on copyright.