ISO is an important aspect of digital photography to have an understanding of if you want to gain more control of your digital camera. Experiment with different settings and how they impact your images today – particularly learn more about Aperture and Shutter Speed which with ISO are a part of the Exposure Triangle. High ISO means high level of noise. And high noise in an image means more grainy looking picture with missing details. It eventually results in an image full of noise that is lacking sharpness and clarity. So select your ISO wisely and make sure it doesn't result in noise.

The ISO setting of your camera directly affects the noisiness in your pictures. A larger ISO allows you to use faster shutter speed and smaller aperture. The ideal ISO to use is 400 - 800 (it differs from situation to situation).

Let us find out such situations where you might need to use a higher ISO settings:

Indoor Sports Events

Sports event or any other activity where your subject is moving fast and there is very limited light to shoot. This is a situation where you may need a high ISO to compensate for low lighting condition.
   

Concerts

Concerts are again a low or dim lighted zones, where you may need a high ISO to take a picture.
   

Art Galleries, Churches etc.

Many Art Galleries these days do not allow using flash when you take a picture. And being indoors, there isn't enough light to capture the details. So, you may need a high ISO to do so. Same is the case with Churches, they are not well lit. Or the available light is dim and diffused.
   

Birthday Parties

The best birthday shot is when the person blows out the candles in dark room. This is when you need a higher ISO to capture it. Using a flash will ruin it completely.