Alcohol is a kind of drink that grown-ups like to have when they are happy, at a party, or just to relax. It's okay to have a little bit, but if people drink too much alcohol all the time, it can be a problem. This is called alcoholism.
When someone drinks too much for a long time, their body starts to get used to it, and they may need more and more alcohol to feel normal. This is similar to getting used to eating too much chocolate or candy, and needing more and more to feel satisfied.
Alcoholism can make people feel sick and make bad choices, like driving a car when they shouldn't or saying mean things to their friends and family. Drinking too much can also hurt their body and make them sick. Some people can't stop drinking, even when they want to, and this can become very dangerous for them.
If someone you know has a problem with alcohol, it's important to talk to a grown-up you trust, like a teacher or a parent, so they can get the help they need to get better.