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Facebook is rolling out the "I'm a Voter" button across the world during elections this yearReuters

When UK voters head to the polls on Thursday to decide who will represent them in the European Parliament, they will be able to click a new "I'm a Voter" button on Facebook.

The feature broadcasts the fact that the user has voted to their entire Facebook friends list, and the social networking site plans to make the button available to citizens worldwide in time for elections in their respective countries.

Previously, the "I'm a Voter" button was only made available to US citizens during the 2010 and 2012 US elections.

Over the last month, Facebook trialled the "I'm a Voter" feature in India and over four million Indian voters clicked the button to show they had voted during the parliamentary elections.

The new button will be available for European voters for the European Parliament elections and Colombian elections over the next week, and will also appear during elections later this year in South Korea, Sweden, Scotland, New Zealand, Indonesia, Brazil and the US.

A 2012 study published in Nature looking at whether the online world can influence the real world found that 340,000 additional citizens decided to vote in the 2010 US elections after seeing that their Facebook friends had voted too.

"Our study shows that the truth is somewhere in between: online networks are powerful ... but it is those real-world ties that we have always had that are making a difference," said James Fowler, a University of California political scientist, who led the study in collaboration with Facebook's data-science team.

Facebook currently has 1.1 billion active users and estimates that almost 400 million users will see the notification that their friends have voted come up on their news feed this year.