The relaxation of coronavirus rules over the festive season has been heavily curtailed across the UK.
Leaders in England, Wales, Scotland and Northern Ireland initially agreed that groups of up to three households could meet at home, outdoors or in a place of worship from 23 to 27 December.
However, following the emergence of a new strain of the virus in the South East, Boris Johnson has announced new rules for Christmas in England, while Scotland, Northern Ireland and Wales have all adjusted their rules as well.
The five-day Christmas bubble period has been reduced to just Christmas Day for England, Wales and Scotland - and scrapped completely for areas in England under new Tier 4 rules - but remains in Northern Ireland.
What can people across the UK do over Christmas?
In England and Scotland, apart from areas in England's Tier 4, a Christmas bubble of up to three households will be allowed to meet on Christmas Day - not from 23-27 December as was previously announced
In Wales, only two households can form a bubble for Christmas Day
In Northern Ireland, three households can form a bubble from 23-27 December, however, from Boxing Day people are being urged to only leave home for essential reasons for six weeks
A Christmas bubble can only meet in a private home, a place of worship or public outdoor spaces
Except for those in England's Tier 4, people can continue to meet others who are not in their Christmas bubble outside their home, but they must adhere to the rules in the tier they are staying in - see the tier explainer here
Travel restrictions across Wales, England and Northern Ireland will be lifted on Christmas Day, allowing people to travel across the nations or between local tiers in order to meet with those within their bubble - apart from people in England's Tier 4 areas
There is a "strict" travel ban between Scotland and the rest of the UK
Anyone travelling to or from Northern Ireland may travel on the 22 and 28 December, but should only meet with their Christmas bubble between 23 and 27 December
Once a bubble is formed, it is fixed and must not be changed or extended further at any point
Children under 18 whose parents do not live together may be part of both parents' Christmas bubbles, if their parents choose to form separate bubbles
Students are considered to be part of the household to which they have returned for Christmas and are not treated as part of their term-time household for this period
Existing support bubbles count as one household towards any household limit. This means that if you are in a support bubble, you can collectively form a Christmas bubble with two other households in Scotland and England, and one other in Wales.
How many households can be in a Christmas bubble?
Initially, the plan across the UK was for up to three households to be allowed to form one Christmas bubble.
However, following a rise in infection rates since the announcement of the Christmas plans, those rules have now changed.
The three household rule still applies in most of England - only those in Tier 4 will not be allowed to mix at all on Christmas Day.
For Scotland, a maximum of eight people from three households can meet on Christmas Day, however advice is to minimise the numbers and keep things outdoors if possible.
In Wales, only two households will now be able to gather together indoors.
And in Northern Ireland, bubbles can include three households.