“Exposure” is foundational to photography, and one of the first diagrams that photography students often see is some version of the (unhelpful) exposure triangle:
As well-intentioned as this diagram is, I’ve never found it to be all that helpful. It only made sense to me after I already understood exposure. It’s also missing an extremely important element – the amount of light available to expose a photo in the first place!
Rathan than a triangle, the Exposure Contraption demonstrates exposure as a scale. On one side, we have the amount of light itself along with ISO, which acts as sort of a “light multiplier.” On the other side we have aperture and shutter speed, both of which govern how much of that light is allowed into the camera. When the scale is balanced, we get a properly exposed image. When it’s not balanced, we get some degree of under- or over-exposure.
I hope the Exposure Contraption gives you a different and helpful perspective on the very important topic of exposure.