Legal drinking age

The legal drinking age is the minimum age at which a person can legally consume alcoholic beverages. The minimum age alcohol can be legally consumed can be different from the age when it can be purchased in some countries. These laws vary between countries and many laws have exemptions or special circumstances. Most laws apply only to drinking alcohol in public places with alcohol consumption in the home being mostly unregulated (an exception being the UK, which has a minimum legal age of five for supervised consumption in private places). Some countries also have different age limits for different types of alcohol drinks.
The most commonly known reason for the law behind the legal drinking age is the effect on the brain in adolescents. Since the brain is still maturing, alcohol can have a negative effect on the memory and long-term thinking. Alongside that, it can cause liver failure, and create a hormone imbalance in teens due to the constant changes and maturing of hormones during puberty. Young people are also especially at increased risk of injury when drinking alcohol. They may not have the necessary knowledge of low-risk drinking. Indeed, public health researchers found that people’s age at drinking the first full serve of alcohol was significantly associated with knowledge of low-risk drinking and drinks counting. The levels of knowledge of low-risk drinking and frequency of drinks counting increased with age at first drink of alcohol more steeply during adolescence than in the later period.
Africa.
The most common minimum age to purchase alcohol in Africa is 18. However, Angola (except Luanda Province), Central African Republic, Comoros, Equatorial Guinea, Guinea-Bissau, Mali, and Togo have no laws on the books restricting the sale of alcohol to minors. In Libya, Somalia and Sudan the sale, production and consumption of alcohol is completely prohibited.
Americas.
In Central America, the Caribbean, and South America the legal drinking age and legal purchase age varies from 0 to 20 years (see table below). In South America in particular, the legal purchase age is 18 years, with two exceptions:
In North America the legal drinking age and legal purchase age varies from 18 to 21 years:
In the late 20th century, much of North America changed its minimum legal drinking ages (MLDAs) as follows: 
Europe.
Most countries in Europe have set 18 as the minimum age to purchase alcohol. Although Austria, Belgium, Denmark, Germany, Gibraltar, Liechtenstein, Luxembourg, Malta, Serbia and Switzerland (except Ticino) maintain a minimum purchase age below 18 years permitting minors either full or limited access to alcohol. In 2005, 2007 and 2015 harmonization at the European Union level toward a minimum purchase age of 18 was discussed, but not agreed.
Timeline of changes to drinking/purchase age or laws restricting the access to alcohol for minors: