People in the UK can work together to beat coronavirus by staying at home, Prime Minister Boris Johnson has announced.
He said he was bringing in new rules that mean people will only be able to leave their homes for a handful of special reasons, but it would help to stop it spreading.
Mr Johnson said he did not want to bring in the rules but it was the only way stop the spread of the virus and stop too many people falling ill at once.
He added if that happened, doctors and nurses might not be able to cope.
But he said by staying indoors, "we will beat coronavirus and we will beat it together".
"If your friends ask you to meet, you should say 'no'," he explained.
"The time has now come for us all to do more.
"You must stay at home."
He announced the new rules for people to follow in a televised address to the nation on Monday night.
Mr Johnson said you can only leave your home to:
- shop for things you really need, like food or medicine
- for exercise once a day either on your own or with people you live with
- for medical reasons or to help elderly or vulnerable neighbours
- grown-ups can travel to work but only if it is essential and they cannot work from home.
He said all shops selling things that weren't essential would have to close. Parks will stay open for exercise but playgrounds will be shut, as well as libraries and places of worship like churches and mosques.
The prime minister also said he did not want people to gather in groups of more than two, unless it is people they live with.
He finished by saying the rules would be looked at again in three weeks - when they might be relaxed if they had worked.
Some countries around the world have similar rules in place to help them defeat coronavirus.
Remember, when big changes like this happen, it can make you feel scared or confused - but that's completely normal.
If you are worried about coronavirus, psychologist Laverne Antrobus has some tips you can follow here.