This video shows some things that I wasn’t exposed to except through years of experience in working with leather. If you are sensitive to animals, I suggest you not watch it, but remember mankind has been doing this beyond history.
(The music needs to be taken out of it so you can see how leather is created)
For more info regarding the finishing that makes all the variations of leathers you’ve seen on furniture or clothing. Here’s a video you could watch that doesn’t have that obnoxious music.