Prime Minister Boris Johnson has said people in England "should be wearing" face masks or other coverings inside shops, to help prevent the spread of coronavirus.
People in Wales will need to wear a mask or face covering on public transport from 27 July.
Face coverings are worn to help stop those wearing the masks from spreading the virus, rather than catching it.
The prime minister said the government would decide in the next few days if "tools of enforcement" - for example new rules or laws - were needed, to make sure people do follow this advice.
But Labour, the opposition party in the UK parliament, has accused the government of having "a lack of clarity" on the issue.
On Sunday one of Mr Johnson's cabinet ministers Michael Gove said that he did not think face coverings should not become compulsory in shops in England.
But he did add: "I think that it is basic good manners, courtesy and consideration, to wear a face mask if you are, for example, in a shop."
Remember, there are different rules about when and where you need to have a mask or face covering depending on where you live in the UK.
You should always wash your hands before and after putting your face covering on, and wash the mask every time it has been used.
Washing your hands properly - and regularly - and social distancing where possible are still as important as ever for preventing spread of the virus.