There is no formula that makes a picture influential. Some images are on our list because they were the first of their kind, others because they shaped the way we think. And some made the cut because they directly changed the way we live. What all 100 share is that they are turning points in our human experience.

I mentioned this upcoming series earlier this month and now it’s available. While all the images are incredible, fair warning: some are disturbing and might upset some people.