Image Source:  https://www.britannica.com/biography/Robert-Frank

I was introduced to Robert Frank's work in my History of Photography and landscape photographers.  In the interview, he explained his perceptions on what makes a good shot, one has to be quick, take the shot when the subjects "are not aware of the camera" - the best shots. I also read and viewed his documentary works at https://www.moma.org/artists/1973.