People must continue to play their part in stopping coronavirus, Boris Johnson has said, as lockdown rules ease in England, Wales and most of Scotland, APA reports citing BBC.
Millions of people can now socialise indoors in limited numbers, hug loved ones and visit pubs and restaurants inside again.
The ban on foreign travel has also been lifted and replaced with new rules.
But Mr Johnson said everyone still needed to be cautious, and also get tested twice a week.
"Together we have reached another milestone in our roadmap out of lockdown, but we must take this next step with a heavy dose of caution," said the prime minister.
He added that "everyone must play their part - by getting tested twice a week, coming forward for your vaccine when called and remembering hands, face, space and fresh air".
"I urge everyone to be cautious and take responsibility when enjoying new freedoms today in order to keep the virus at bay."
Anyone in England and Scotland can order free lateral flow tests - which give results in 30 minutes - even if they do not have symptoms. In Wales and Northern Ireland, they are available for certain people, such as those who cannot work from home.