Coffee, a hot drink made from the roasted beans (seeds) of the coffee tree. Coffee is a popular beverage in North America, commonly consumed at breakfast or during the morning "coffee break" at work. It contains 1 to 2 per cent caffeine, a substance that stimulates the central nervous system. Caffeine increases wakefulness and alertness, but excessive amounts can cause a number of unpleasant symptoms. Persons who regularly drink more than five cups of coffee daily may experience withdrawal symptoms if they stop drinking it.