People across Britain are heading to the polls for the biggest set of votes since the 2019 general election.
Millions are set to cast a ballot in elections for the Scottish Parliament, the Welsh Senedd, and 143 councils and 13 mayors in England.
A Westminster by-election is also taking place in Hartlepool.
Polling stations opened at 07:00 BST and will close at 22:00 BST, with the results expected over several days.
Up to 48 million people across Britain are eligible to vote in the bumper set of elections, on what has been dubbed “Super Thursday”.
Some of the polls were due to be held last year but the Covid pandemic forced their delay, meaning more than usual are taking place this time.
Voters in England and Wales will also select 39 police and crime commissioners and voters in London will choose who sits in the London Assembly.
Polling stations are observing strict Covid protocols, including the frequent cleaning of booths.
Social distancing will be in place, and voters are being encouraged to bring their own pencils for completing ballots.
Voters who registered to do so can also return their ballots by post, or have a nominated person vote on their behalf (proxy voting).
Those who have to self-isolate because of Covid have until 17.00 BST to apply for an emergency proxy vote.
The Democracy Club group – which encourages voting – says more than 35,000 venues across Britain will serve as polling stations.
These include more than 50 restaurants and cafes, 30 museums, 120 cricket clubs and pavilions and 13 boxing clubs.
When will the results be known?Some counting will take place overnight on Thursday, including for the Hartlepool by-election, where a result is expected in the early hours of Friday.
Results for all 60 seats in the Welsh Senedd will be known on Friday.
Scotland starts counting in some areas on that day, but there will not be a final result until Saturday, or possibly Sunday.
Counting in council areas in England will take place on Friday, and continue over the weekend in some areas.
And 12 of the counts for the 35 police and crime commissioners being elected in England will not begin until Monday.