Exposure triangle research

 The exposure triangle is a system used when taking a photo and by extension can be applied to film and serves the purpose of controlling how the image looks by adjusting focus, picture quality and light amongst other things, the exposure triangle can be broken down into 3 different factors thus the triangle featured in the name

The first of these 3 things is the aperture which controls the amount of light let in by the camera by controlling how open the lens is  

The amount of the lens that is open is assigned a number which is used to measure the aperture, smaller aperture equals a larger number and vice versa 

https://www.google.co.uk/amp/s/photographylife.com/what-is-aperture-in-photography/amp

by manipulating the exposurre triangle different types of lighting can be created in photos or film to suit the needs of the shot, being able to effectivly utelise the exposure triangle will mean being able to effectivley control the way light appears in your shot