While the alcohol industry promotes alcohol as the essential ingredient for a happy, sociable life, individuals, families, communities and countries experience its harms. This chapter clarifies the various terminologies that are used to describe alcohol use and misuse, and explains how alcohol, a toxic substance, damages the human body and causes diseases which can be fatal. In small amounts, alcohol may make people feel relaxed and confident, but this can tip into using alcohol to numb emotions, to self-medicate, and to relationship breakdown, aggression, violence and crime. The costs of alcohol, borne by the public, are personal, social and financial. The UK’s Low Risk Drinking Guidelines explain how to drink so that the risks to health are minimised, but only drinking no alcohol is completely safe. Trends in UK alcohol consumption are falling, but alcohol misuse, heavy drinking and binge drinking are too high. Alcohol use and misuse is a biological, psychological and social phenomenon, and some of the benefits of reducing and giving up alcohol are presented.