Additional details:
Chicks molt quite a few times as they grow up. First they grow tiny chick feathers, then later they are bigger so they lose the tiny feathers and get bigger feathers, and this happens several times before they reach adulthood. When chicks molt, they usually replace a few feathers at a time, so you might notice small bald patches or you might not notice anything.
Once they are grown up, it is common for them to molt once a year, although some adult chickens do partial molts more often than that.