Smoking in enclosed public places across the UK is now against the law, after England became the last part of the country to ban it.
The new rules came into effect at 6am on Sunday morning, making it illegal to smoke in places like cafes, offices, shopping centres and train stations.
Scotland, Wales and Northern Ireland already have bans in place.
The government hopes the new law will cut the number of people who die from illnesses caused by smoking.
Smoking is really bad for your health and is also very expensive.
It's hoped the ban will encourage more people quit and stop children starting the habit.
But some people are worried it will mean your family will smoke more at home, where it can affect you too.