However, the more signals are boosted, the more noise is generated, which is equivalent to the grainier image that appears in analog film at ISO 1600 and higher. Unless a grainy effect is desired ...

An ISO of 200 is the average daylight setting. Image caption, The images are becoming progressively more grainy as ISO increases. At the top left of the scale, ISO 100 shows a clear image.

Low-light situations require higher ISO settings, but these can result in image noise that is visible in grainy elements in darker parts of the image. This is why photographers try to avoid high ISO ...

An ISO of 200 is the average daylight setting. Image caption, The images are becoming progressively more grainy as ISO increases. At the top left of the scale, ISO 100 shows a clear image.