Cameras really are their own foreign language. In order to be able to tell your camera how you want your picture to turn out, you have to be able to communicate with it. DSLR's have their functions located in a quick, accessible place to be able to assist you. But if you don't know what they do or what they mean, that "Auto" setting looks pretty tempting! To help you out, I thought I'd define what they all meant! (Don't worry if you shoot Cannon, I'll be your translator - because making everything universal would be to easy.)

For starters, I made up this quick graphic of what the dial looks like on my Nikon D750. If you're fretting about the black circle button in the middle, don't mind that. It is just the button you push while turning the dial. They made it like that so that you could "lock" in what setting you want to shoot in. It doesn't matter if your camera has one or not - it won't effect what they symbols mean. 

M - MANUAL 

     - This one is pretty easy to guess right off the bat, (and it's the same for Canon.) By using this setting you have total control of every setting for your camera. You tell it what to do.

A - APERTURE PRIORITY

     - Aperture priority means that the user sets the aperture and the camera sets everything else up to give a proper exposure. That means if you want to shoot something at F1.4, the camera reads the light and decides what shutter speed and ISO to use in order to have the picture be exposed correctly. (If you want to learn more about Aperture, read my post on it, here.) (AV mode on Canon)

S - SHUTTER PRIORITY

     - The user chooses the shutter speed and the camera adjusts aperture and ISO to produce a properly exposed image. (If you want to learn what the heck ISO is, you can read my post about it here.) (TV mode on Canon)

P - PROGRAMMED AUTO

     -The camera automatically adjusts aperture and shutter speed for optimal exposure, but the photographer can choose from different combinations of aperture and shutter speed that will produce the same exposure. This is also known as flexible program. (P on Canon)

AUTO

      - The camera has full control of the shot.

NO FLASH

     - Another form of "Auto" only this time - regardless of the situation, the camera will not use flash. 

SCENE

     - Remember when everyone had cameras before they were attached to our phones? This is the setting you can use to set it to the "flower" for macro or the "running guy" for sports. Basically you take what your environment looks like and assign it to a preset shooting setting. 

U1 + U2

     - The user can assign frequently used settings to these positions on the dial