In photography, the exposure triangle represents three elements that when equally balanced, produce the sharpest and best looking photos. Although, there are some exceptions to this since photography is subjective. For example, by not balancing the triangle, you can produce a unique artistic style. The three elements of the triangle are Aperture, Shutter Speed, and ISO.
Aperture: Simply put, aperture is the amount of light that reaches the cameras sensor. Aperture is measured in F Stops. The smaller the number, the larger the opening (larger openings allow for more light to reach the sensor)and the larger the F number, the smaller the opening. This can feel backwards to many beginners but when broken down as a mathematical equation, it makes perfect sense.
Shutter Speed: Think of this like blinking your eye. A fast shutter speed (ex 4000/second) is very quick and a long shutter speed (ex 1 second, 30seconds, or sometimes even several minutes) When you use a fast shutter speed, not very much light is able to enter your camera.
ISO: (International Organization for Standardization) This is the shutters sensitivity to light. Think of if you wake up after a deep sleep and turn on the lights. Your camera is adjusting to the aperture light condition.
These three elements must be balanced correctly to produce the most desired results. If your image has too high of ISO, the result is a grainy looking photo, one with high “noise“. Modern day cameras have a meter that constantly works to balance these by allowing you to control two of the three settings.