Understanding the basics of the exposure triangle-
There are 3 elements involved in exposure (hence, triangle)
• Aperture (the amount of light that passes through the lens)
• Shutter Speed (the amount of time the shutter is open to allow in light)
• ISO (the film or sensors sensitivity to light.)
When you change one element of exposure, you alter the other two elements. This image will give you a basic understanding of what the 3 different sides of the exposure triangle are capable of.