From 8 June all those arriving from overseas into the UK, including returning British residents, will be required to self-isolate for 14 days.
The quarantine will apply to anyone arriving into the UK by plane, train or ferry.
It will be reviewed by the government every three weeks. The first review will be on 28 June.
Only those working in designated cross-border jobs, such as lorry drivers, seasonal agricultural workers and medical staff providing essential health care, will be exempt. The common travel area with Ireland, the Channel Islands and the Isle of Man will be unaffected by the measure.
What happens on arrival in the UK?
Everyone, other those who are exempt, will be required to fill in a contact locator form with contact and travel information so they can be reached if they, or someone they may have been in contact with, develops coronavirus.
Friends and family can collect travellers from the airport, port or station.
Travellers should only use public transport if they have no other option. If they do choose to use public transport, they should wear a mask or something that covers the nose and mouth, and stay two metres apart from others.
If the traveller does not have somewhere to stay, accommodation will be arranged by the government.
What is allowed while under quarantine?
The rules are similar to those that apply to individuals who are self-isolating with coronavirus symptoms.
Arrivals will be allowed to leave isolation to shop for food essentials, seek urgent medical attention and support from social services, to collect medicines if they cannot be delivered, and attend a funeral of a close relative or an emergency.
Visitors, including friends and family, are not allowed, unless they are providing essential care.
The Scottish Government announced on 7 June that failure to complete the locator form prior to arrival or refusing to complete it could result in a £60 fixed penalty notice rising on an incremental scale to £480. Breaching self-isolation could result in a fixed penalty notice of £480.
Persistent offenders can be reported to the Procurator Fiscal which could ultimately result in prosecution and conviction with a maximum £5,000 fine.
In England, a breach of self-isolation is punishable with a £1,000 fixed penalty notice or potential prosecution and unlimited fine.
Spot-checks will ensure they are staying at the address or addresses they have provided to the authorities.
Is there an alternative to quarantine?
The travel industry and politicians are calling for “air bridges” to be introduced, allowing quarantine-free travel to and from countries with low Covid-19 infection rates.
However, the UK has some of the worst infection rates in Europe which will make other countries wary of accepting visitors or allow their citizens to travel to the UK.
Italy this week said it would allow Britons to enter without quarantine, but it is not clear whether Italy will encourage its citizens to travel to Britain. Greece and Portugal have also backed air bridges.
France may be willing to do a deal with Britain that could allow some travel to continue.
What are the restrictions on travel?
The UK government only recommends travelling internationally if it is essential.
Social distancing measures must be followed during your journey and face coverings are recommended as a precaution.
The Foreign Office also warns that travellers must be aware that countries may restrict travel and close their borders without notice if the outbreak worsens, raising the prospect of being stranded overseas.
What is happening elsewhere?
New Zealand, South Africa, South Korea, Spain and the US are among countries that already require arrivals to undergo a 14-day quarantine.