Hi, I just recently got interested into photography and I was wondering if someone could answer a few questions on "different exposures" (not sure if I am using the right term). From what I understand, exposure is basically a relationship between Aperture, Shutter Speed, and ISO. Could someone verify whether this is correct or not? Also, how do I know when to use different exposures (i.e different combinations of Aperture, Shutter Speed, and ISO)? Are there any rules of thumb I need to keep in mind? Thanks in advance!