A night cream is essentially just a cream you put on at night. People have been doing this since Roman times when olive oil was used to help guard against wrinkles.
Night cream can be typified however as being heavier than other moisturisers or Day Creams in their active ingredients to help boost skin repair. Research has shown that your skin cells act differently through the day. During the day working to protect you from environmental factors while at night concentrating on protecting themselves.