Dependence is the state of being addicted to a substance — the point where the body or mind has adapted to its presence and functions poorly without it. Physical dependence shows in tolerance, needing more for the same effect, and in withdrawal symptoms when the substance stops; psychological dependence shows in craving and compulsive use despite harm. In the food and drink world the concept centres on alcohol, caffeine, and nicotine, but it also frames debates about sugar and highly palatable processed foods — whether they can produce addiction-like patterns is one of nutrition’s liveliest arguments. Clinicians distinguish dependence from casual heavy use by the loss of control and the withdrawal syndrome. Treatment combines medical management of withdrawal with behavioural change. The word marks the boundary where consumption stops being a choice and becomes a compulsion.