Refers specifically to cow's milk, the most common type of milk in Japan. For other animal milks, the animal name is usually prefixed (e.g., ヤギの乳).
毎朝、牛乳を飲みます。
I drink milk every morning.
この牛乳は賞味期限が切れている。
This milk is past its expiration date.
I drink a glass of milk every morning.
I warmed the milk in a pot to make hot milk.
I poured milk into the cup.
I left the milk out on a hot day and it went bad.
powdered milk; dried milk
certified milk