A number of new lockdown measures have been introduced by Prime Minister Boris Johnson - this is what they all mean.
When can you leave your home?
People will only be allowed to leave their house for limited reasons.
Mr Johnson said residents can leave their homes for shopping for necessities such as food and medicine, but only as infrequently as possible.
Exercise will be allowed - preferably limited to once a day - with members of your household or support bubble or one other person from another household, such as if going for a walk or run.
People will be able to go to work if it is impossible to work from home, such as those working in the construction sector or who are critical workers. All others must work from home.
Cleaners and other trades people will still be able to work in people's homes.
Schools to close
All schools, including primary, secondary and colleges, are set to close to the majority of students under the new guidelines, and move to remote teaching. Children of essential workers, or those who are vulnerable will still be able to go to school.
The Prime Minister also confirmed that exams set for summer 2021 will not go ahead as planned and that conversations with exams boards will take place.
Early years settings such as nurseries and childminders can remain open, and existing childcare bubbles will be allowed to stay in place.
University students will not be allowed to return to campus and will be expected to study from their current residence.
In-person university teaching will only take place for a small number of critical courses.
Non-essential shops to remain closed
All non-essential shops will remain closed, as they were under the previous tier four restrictions.
However essential shops, such as food stores, garden centres and pharmacies will remain open under the new guidelines.
Closures include hairdressers, nail bars and all other personal care venues.
Work from home
Just like the previous lockdown which started in March 2020, people are asked to work from home when possible.
Those with jobs which cannot be done at home, can still go to work but are asked to follow social distancing rules and follow the 'hands, face, space' guidelines.
Vulnerable should start shielding
Mr Johnson told those who are clinically vulnerable to begin shielding again, as they did during the first lockdown in March.
He said vulnerable people should stay at home and only leave for medical appointments and exercise.
They are advised not to go to work even if they cannot work from home.
Sport and other activities
Playgrounds will remain open, but outdoor gyms, tennis courts and golf courses must close, and outdoor team sports will not be permitted.
Premier League and other elite sports that already have in place strict testing regimes and their own bubbles will be allowed to continue.
Social bubbles to stay in place
The government have confirmed that social bubbles with adults who live on their own will remain in place.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here