In Vatican Square, tens of thousands greeted Pope Francis. But in cyberspace, it was more like tens of millions from all around the globe.
One of the first Tweets was "HABEMUS PAPAM FRANCISCUM" -- the Latin phrase translates to "We have Pope Francis" -- from the pope's official Twitter account, @Pontifex.
The British prime minister wrote: "A momentous day for the 1.2 billion Catholics around the world as His Holiness Pope Francis the First is appointed the 266th bishop of Rome."
Meanwhile, former Sen. Rick Santorum Tweeted: "let us pray for Pope Francis!"
Another well-known politician, Jeb Bush, exclaimed: "Wonderful news of the selection of Pope Francis, the first Latin American pope."
Media from around the world Tweeted away, too.
England's BBC posted a papal photo capturing the "moment new pope appeared on Vatican balcony -- Jorge Mario Bergoglio of Argentina."
Israel's Haaretz newspaper Tweeted: " Catholic church has a new pontiff: #Pope Francis from Argentina."
And when it comes to following the new pope, no worries: there's an app for that. The Pope app will let you watch and listen to all the pontiff's public speeches and ceremonies.