A Jan. 12, 2012 file photo, shows the Facebook "like" icon displayed outside of Facebook's headquarters in Menlo Park, Calif. Paul Sakuma/AP Photo

Facebook has launched a global version of its "I'm a Voter" button. So, what is it good for and what can you do with it?

Share your voting status:

Think of it as a digital version of the "I voted" sticker. The concept is easy: You click the megaphone button and Facebook will add a badge to your profile, letting your Facebook friends know that you voted. But it won't broadcast who you voted for.

Facebook estimates that 400 million people around the world will see the button show up in their news feeds this year.

Encourage your friends to vote:

A study in the prestigious science journal Nature found that in 2010, 340,000 additional people in the United States were encouraged to vote in the midterm elections after seeing that their friends had voted. Facebook's "I'm a Voter" button debuted in 2012, when President Obama was re-elected and an estimated 9 million Americans shared the button.

But the new version, announced Monday, will take the feature global.

India was a test case for the button in its recent nine-phase voting process in April and May. An estimated 4.1 million Indians used the button to digitally announce to their Facebook friends that they had voted in the 16 th election for the Lok Sabha - the lower house of the country's parliament. Here's what it looked like:

Courtesy Facebook

Facebook plans to roll out the "I'm a Voter" button in the European Parliament, Colombia, South Korea, Indonesia, Sweden, Scotland, New Zealand, Brazil and again in the United States this year.