EXPOSURE TRIANGLE
One of the most basic concepts in photography is the exposure triangle. If you choose not to set your camera to auto mode, you must know when and how to use each setting in order to have a picture perfect photo every time. In this clip, Mark Wallace does a great job of detailing the exposure triangle. I think it’s a great resource for all photographers and a must see for beginners in the field: Below is a link to an article and videos about the subject.