Alcohol law is a set of rules about drinking and owning alcohol. These rules are set by the government and are different in every country, state, and county.
In some places, it's against the law for people who are younger than 21 to buy, own, or drink alcohol. That means if you are younger than 21 and you try to buy alcohol from a store, or if you are caught drinking alcohol in a park, you could get into trouble with the police.
In some places, only certain places are allowed to sell alcohol, like stores and restaurants. That means it's against the law to buy alcohol from other places, like on the street, or to make alcohol in your own home.
In some places, you need a special license or permit to be able to sell alcohol in a restaurant, bar, or store. That means if a business wants to sell alcohol, they need to get a license from the government and follow the rules about selling it.
Overall, following alcohol law is very important. It is the law, and it helps to keep people safe.