Scotland has introduced minimum unit pricing on alcohol as it tries to improve public health by raising the cost of cheap, strong drinks favoured by young people and binge-drinkers.
Minimum unit pricing sets a floor price for a unit of alcohol, meaning it cannot legally be sold for less than that. The more alcohol in a drink, the more expensive it will be.
A unit of alcohol, defined as 10 millilitres (8g) of pure alcohol, must not cost less than 50 pence in Scotland.
The increase on mainly cheaper white ciders and value spirits will help to cut alcohol-related deaths, according to the Scottish government.
First Minister Nicola Sturgeon said Scotland had led the world by becoming the first country to implement such a measure, and hailed the policy as "bold and brave".
The minimum 50p per unit price was delayed for six years by a legal challenge led by the Scotch Whisky Association.
Today's measure has been welcomed by the medical professional and health campaigners as the biggest breakthrough in public health since the ban on smoking in public.
Speaking on a visit to Edinburgh, Ms Sturgeon said: "Scotland is the first country in the world that is being bold enough and brave enough to implement minimum unit pricing.
"The eyes of the world will very much be on Scotland, not just today but as the benefits of this policy start to be seen and felt.
"Already we see countries across the British Isles - Wales and Ireland - looking to follow suit and I'm sure that as the benefits of this policy start to be seen we'll see other countries elsewhere doing exactly that.
"All of the evidence says that minimum unit pricing will reduce deaths from alcohol-related illnesses, reduce hospital admissions and generally reduce the damage that alcohol misuse does to our society.
"No one has ever said that minimum pricing on its own will resolve all of the problems we have with alcohol misuse but all of the experts who support this policy will also say that without this all of the other things we do will not have as much impact as we want them to."
It is estimated the move could save around 392 lives in the first five years of its implementation in Scotland, where on average there are 22 alcohol-specific deaths every week and 697 hospital admissions.
The misuse of alcohol is thought to cost Scotland £3.6 billion each year, or £900 for every adult in the country.
Minimum unit pricing is planned for Ireland under the Public Health (Alcohol) Bill.