In the art of photography a couple of questions need to asked, one of those questions are, what is the exposure triangle? As a serious photographer no matter the level, you need to know this. You can achieve any shot you want by understanding this triangle, ISO, Shutter speed, and Aperture are the three elements of the exposure triangle.

So what is the exposure triangle?

The exposure triangle consists of three elements that adjust how a camera captures light, these three are the reason for a shot being properly exposed. ISO, Shutter speed, and Aperture are all dependent on each other, if you’re adjusting one of the three elements you will need adjustment of another to maintain proper exposure. Aperture, shutter speed, and ISO are the primary variables of the camera triangle that control exposure. However, each variable also affects other qualities of an image. Depth of field, motion blur, and noise are all determined by elements of exposure triangle photography.

Aperture

Aperture is the most important of the exposure triangle so it’s crucial you understand it, Terms like F-stops and depth of field may alarm beginner photographers, but not really that complicated.

Wide aperture (e.g., f/2.8, f/4, f/5.6)
Narrow aperture (e.g., f/16, f/22)

Shutter speed

It’s the speed at which the shutter of the camera closes, a fast shutter speed lets in less light into the camera and a slow shutter speed lets in more light. The faster shutter allows you to freeze time, but with a slow shutter the photographer gets a long exposure.

ISO

ISO is your camera's sensitivity to light. The lower ISO value means less sensitivity to light, while the higher ISO means more sensitivity. The higher you go up in sensitivity you may start to see grain in your image, that can be from 1600 and up.

Take the time to get to know this, it will make you a better photographer no mater the level you will like to Pursue.