A National Health Service app that aims to track the spread of coronavirus is being rolled out for the first time, as part of a trial on the Isle of Wight in the UK.
Council and healthcare workers were the first to try the contact-tracing app, with the rest of the island able to download it from Thursday.
If the trial is successful, it could be available nationwide within weeks.
Concerns have been raised over privacy, though ministers say the app has been designed with this "front of mind".
The app aims to quickly trace recent contacts of anyone who tests positive for the virus.
It is part of the government's strategy for coming out of lockdown, which aims to have widespread testing and contact tracing in place to monitor and reduce any future outbreaks.
If the trial is successful, the app will be rolled out across the whole of the UK by the middle of May, Health Secretary Matt Hancock said.
Meanwhile, Labour leader Sir Keir Starmer has called for a "national consensus" on tackling the virus when the UK begins to move out of lockdown.
It comes as the number of coronavirus-related deaths in the UK reached on Tuesday 28,734, an increase of 288.
The daily increase in deaths is lower than at any point since the end of March, but the figures reported at the weekend tend to be lower and are expected to rise, Hancock said.
The new app - published on Apple and Google's app stores - works by using a Bluetooth connection.
It records when two people who have the app are within a certain distance of each other for longer than a specified amount of time.
If one of those people later reports having symptoms, all the other app users they came into significant contact with over recent days will be alerted and, if judged necessary, told to self-isolate.
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