What is ISO?

ISO controls the brightness of your photos and controls the cameras sensitivity to light. Put simply, it will lighten or darken your photos. As you increase your ISO, your cameras sensitivity will increase and therefore photos brightness will increase.

Advantages

It means you could have more flexibility in your aperture and shutter speed settings. For example, if you’re indoors with poor lighting and you’re photographing a sports even where people are moving fast, then you would be able to use a fast shutter speed without the photo being under exposed.