People in Scotland are voting on whether the country should stay inthe UK or become an independent nation.
Voters are answering "Yes" or "No" to the referendum question: "Should Scotland be an independent country?"
With 4,285,323 people - 97% of the electorate - registered to vote, it is expected to be the busiest day in Scottish electoral history.
Votes will be cast at 5,579 polling stations until 22:00 on Thursday. The result is expected on Friday morning.
Strict rules mean the BBC - in common with other broadcasters - is not allowed to report details of campaigning until after the polls close.
A number of councils around the country said polling stations were busy, with some seeing queues both ahead of the polls opening and throughout the morning.
Stirling Council area counting officer Bob Jack said: "There has been a steady stream of voters and we have been very busy."
In East Renfrewshire, there were queues before the polls opened this morning and a steady stream since, a council spokeswoman said. Some voters had been kissing their ballots, she added.