When shooting moving objects or taking pictures with your hands, there is a high likelihood of motion and blurry images. This is because the shutter speed is too long for this scene. Increasing the sensitivity of the sensor will slow down the shutter speed. Thus, increasing noise, we reduce blur and as a result we get a clear picture, although not of perfect quality. Without an increase in ISO, a shot would not work at all. Often you have to compromise between a low quality image and a terrible quality image. And, as you know, from two evils... Before raising the ISO, it's worth trying to take a picture with a flash. If this is the right option for your scene. then you can stop.