A really useful article that I have explored to allow me to learn all about the aperture, shutter speed and ISO. ..
The aperture is a small set of blades in the lens that controls how much light will enter the camera. Obviously, if you shoot with the aperture wide open, then more light is allowed into the camera than if the aperture is closed down to only allow a tiny hole of light to enter the camera.
So suppose you take a picture that is too bright. How do you fix it? Simply choose a smaller aperture.
The shutter is a small “curtain” in the camera that quickly rolls over the image sensor (the digital version of film) and allows light to shine onto the imaging sensor for a fraction of a second. The longer the shutter allows light to shine onto the image sensor, the brighter the picture since more light is gathered. A darker picture is produced when the shutter moves very quickly and only allows light to touch the imaging sensor for a tiny fraction of a second.
A high ISO such as ISO 1,600 will produce a brighter picture than a lower ISO such as ISO 100. The drawback to increasing the ISO is that it makes the picture noisier. Digital noise is apparent when a photo looks grainy. Have you ever taken a picture at night with your cell phone or your pocket camera, and noticed that it looks really grainy? That is because the camera tried to compensate for the dark scene by choosing a high ISO, which causes more grain.