Covid measures across Scotland have been relaxed to enable people to meet indoors for Christmas.
Bubbles can be formed with other households and travel restrictions have eased for 24 hours from 00:01.
The original plans to ease restrictions for five days were scrapped following the emergence of a faster-spreading strain of coronavirus.
The toughest level four rules will come into effect across mainland Scotland from Boxing Day..
However Nichola Sturgeon has warned these measures could be further strengthened in a March-style lockdown.
By law a maximum of eight people from three households can meet up – although fewer numbers are recommended and people are encouraged to keep a distance of 2m (6ft 6in) away from those outside their own household.
Those in a bubble can only gather in a private home, outdoors or at a place of worship – but should minimise the length of time spent with the bubble, especially indoors.
People can travel anywhere in Scotland to meet family and friends, but they should not go anywhere else in the UK, unless in exceptional circumstances.
Once level four restrictions are applied, all bars, restaurants and non-essential shops will have to close.
The government is to narrow the definition of “essential retail” – forcing homeware shops and garden centres to close – while guidance urging people to stay at home as much as possible may be put down in law.
People should not travel outside their local authority area at this point and a ban on travel to the rest of the UK will apply over the festive period.
Schools are to stay closed until 11 January, and most pupils will learn from home until at least 18 January – a situation the first minister said would remain “under review”.
The government is also examining whether the current level four measures will be enough to contain the new strain of the virus, which studies suggest can spread up to 70% faster than previous variants.
Nicola Sturgeon said a decision on whether this was necessary would be taken as more evidence about the new variant became available.
A report published by the Office for National Statistics on Christmas Eve suggested the number of people with Covid in Scotland has dropped, but the new strain was responsible for 38% of positive cases.
In her Christmas message, the first minister thanked the emergency services and armed forces who will be working on 25 December, mentioning health and care workers in particular for their efforts over the last year.
She urged people to continue “keeping a distance”, acknowledging the difficulties faced by those who will spend Christmas alone.
Scottish Labour leader Richard Leonard also thanked key workers and offered his condolences to those who had lost a friend or family member “during this most difficult year”.
Douglas Ross, the Scottish Conservative leader, said “forsaking Christmas Day hugs and big family meals this year are for the greater good”.
The Scottish Greens’ co-leader Patrick Harvie referred to the new vaccine, saying “there is light at the end of the tunnel”.
And Willie Rennie, who leads the Scottish Liberal Democrats, said: “For many it’s not the Christmas they had hoped for, but the end of this crisis is in sight and we must all do what we can to get us there safely.”