Exposure compesation

Measuring light on cameras won't always be exact and if we rely only on it, sometimes we'll get underexposed or overexposed photographies. For that to be avoided, in some situations experienced photographer will predict that camera could make a mistake, and he will help it to correct this mistake with help of exposure compensation. This feature is particularly useful when photographing light demanding scenes. The best example is photographing people on snow where camera will be easily confused, and will underexpose photography and by that the person we want to photograph too, because of the high amount of light.