DW picked out four cat pictures and they show four aspects of cat behavior, life, anatomy, you name it. They are very nice pictures of cats too. I understand them to be in the public domain. If you click on the thumbnail image you go to a larger format version and some words about the aspects that I would like to mention.
Pictures of cats are very common on the internet. Have we learned from them or just be amused by them?
Briefly touching on the human aspect, it seems that the explosion on pictures of cats is largely based on our desire to be amused or to make money from the cat. I am thinking of the cheeseburger site and YouTube videos that get millions of hits. I have some millon + hit videos too but the intention is to celebrate the cat.