Noise

Noise appears in photos when high ISO settings have been used.

Here is a section from a photo that was taken using ISO 3200. It shows colour speckles in areas, which is noise.

Always try to use the lowest possible ISO setting that lets you use a fast enough shutter speed to get a sharp (not shaky) shot.

Using too high ISO results in noise. Noise can be problematic, but it can be reducing by image editing applications.

Using too low a shutter peed results in camera shake which cannot be fixed.

It is better to use a higher ISO with a faster shutter speed and have an image with noise, than to use a low ISO and low shutter speed which could result in a blurry photo.