It’s not as sexy as a love triangle and not as dangerous as the Bermuda Triangle. However, the exposure triangle is key to understanding how your camera works. The exposure triangle is also important if you want to nail exposure in a semi-automatic mode or manual mode.
The three things that affect exposure in an image are aperture, shutter speed, and ISO. If you change one of those settings, you must adjust one of the others to compensate. This is where understanding the exposure triangle and stops of light is useful.