Social gatherings of more than six people have been banned across Britain in an attempt to curb the rise in coronavirus cases - but tougher measures are being imposed in the worst-hit regions.
Here we look at the rules that all of us currently have to follow, how they differ in England, Scotland and Wales, and the specific restrictions being enforced in certain areas.
What are the rules on social gatherings?
• Gatherings of more than six people are illegal, unless it meets one of a limited list of exemptions
• This applies to gatherings both indoors and outdoors in England and Scotland, and indoors in Wales
• It applies to all ages in England, and everyone except children under the age of 11 in Wales and under 12 in Scotland
• In Northern Ireland, six people from two different households can meet indoors and groups of up to 15 people outdoors - but localised restrictions have been introduced in Belfast and Ballymena
• Social premises and venues, including pubs and restaurants, are now legally required to request test and trace information from customers and keep the details for 21 days
• Households or support bubbles of more than six people can still gather
• Groups of more than six people are allowed for work or education
• Places of worship, gyms, restaurants and hospitality settings can still hold more than six people in total
• Weddings and funerals are also exempt, with up to 30 people allowed to attend them in England and Wales and 20 people in Scotland
• Organised team sports carried out in a "COVID-secure way" can have more than six people
What happens if you break the rules?
Anyone who breaks the rules on social gatherings will be fined £100, with the penalty doubling on each further repeat offence up to £3,200.
"COVID-secure marshals" will enforce social distancing rules in town and city centres, the prime minister has said.
Border Force are also stepping up the enforcement of quarantine rules for travellers into the country.
Why have the rules been introduced?
According to cabinet ministers, England's chief medical officer Professor Chris Whitty and chief scientific adviser Sir Patrick Vallance have jointly agreed that urgent action is necessary after seeing the number of daily positive cases rise significantly.
There were 3,991 new daily confirmed cases of coronavirus across the UK on 16 September - the highest figure since 8 May.
England's deputy chief medical officer, Professor Jonathan Van-Tam, has warned of a "bumpy ride over the next few months" unless the virus is taken "incredibly seriously".
Which areas are facing local lockdowns?
A number of local lockdowns have been introduced around the UK in response to spikes in coronavirus cases.
The North East
Increased measures have come into force in the region, covering Northumberland, Newcastle, Sunderland, North and South Tyneside, Gateshead and County Durham.
The measures introduce a ban on mixing with others outside your household bubble - and a 10pm curfew for all bars, pubs, restaurants and cafes. This is in place until 5am. Takeaways can only offer delivery service after 10pm.
There is table service only in bars and pubs and restrictions on major events have been introduced.
Rhondda Cynon Taf, Wales
People are banned from entering or leaving the area "without a reasonable excuse".
Households will no longer be able to meet each other indoors or form an extended household and restaurants, pubs, cafes and all other hospitality premises will have to close at 11pm.
The new restrictions will come into effect on Thursday 17 September.
Birmingham, Sandwell and Solihull
People are not allowed to mix with any households, indoors or in private gardens, except for those in a support bubble.
Restaurants, cafes, bars and pubs are restricted to takeaway only - and all hospitality venues are required to close between 10pm and 5am.
A ban on mixing outside households in public outdoor settings is also enforceable by law.
People are not allowed to enter or leave the area without a reasonable excuse.
Everyone over the age of 11 is required to wear face coverings in shops and people should not meet indoors with anyone outside their household.
Belfast and Ballymena, Northern Ireland
Different households are banned from meeting in each other's houses - apart from those who have formed a "bubble" with another household and those with caring or childcare responsibilities.
In addition, no more than six people - from no more than two households - can gather in private gardens, while residents are urged to avoid unnecessary travel outside the local areas.
Parts of Greater Manchester, East Lancashire, Preston and West Yorkshire
People cannot meet anyone from outside their own household or support bubble in a home or garden.
People living in Glasgow City, East Renfrewshire, Lanarkshire and West Dunbartonshire are banned from meeting people from another household inside their home.
People have been told not to meet anyone from another household in a home or garden, unless they are in their support bubble.
Which areas are likely to face further restrictions?
Tougher measures are expected to be announced in Lancashire - with the exception of Blackpool - Sky News understands.
Under the new restrictions, people from different households would not be allowed to meet in homes, private gardens, public parks, restaurants, and pub beer gardens.
People will only be encouraged to use public transport for essential trips.
According to reports, Merseyside and Leeds could also be next to be placed under similar restrictions.