Learning even just the basics of photography takes a bit of work and one of the more complex ideas is the relationship between ISO, aperture, and shutter speed. Lifehack has a graphic that helps make sense of it.
"Faces in the Rubble In the Bronx, Capturing Beauty in the Bad Old In the middle of a Mott Haven street, a lone couple hugs tightly and twirls to the music of an unseen orchestra. Bronx, New York. Photo by By David Gonzalez