powder is used both as a beauty product and for helping to keep the skin dry. if you have oily skin, especially on your face, you'll like need powder to minimise the excess oil and prevent your face from shining.
talcum powder is very commonly used by children and adults. baby powder is used all over the baby's body and also to prevent diaper rash.
  powder helps to absorb moisture on the skin and some people even use it under their armpits as an antiperspirant to prevent sweating.