Pope Francis isn’t the first pontiff to use Twitter, he’s the second. But he’s the first to use it well.

So says author Michael J. O’Loughlin, who wrote the book, "The Tweetable Pope," on Francis’ ability to get the word (or The Word?) out in 140 characters or less. 

“Pope Francis has adopted it as a way to communicate his message,” O’Loughlin said. “He’s lent his name to a number of social media campaigns.”

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Social media exploded with the pope's visit to Philadelphia. 

But he doesn’t tweet while traveling — it’s just too complicated, O’Laughlin said. He typically sends one tweet out as he arrives in a country, asking for prayers. Then tweets again as he leaves. 

The Holy Father tweets in nine different languages to more than 20 million followers, O’Loughlin said. He selects his own topic, and then Vatican officials scan the pontiff’s homilies for passages that conform to the theme. 

O’Loughlin, who works for The Boston Globe’s website devoted to Catholicism, the Crux, said that by some studies, Pope Francis is one of the most effective Twitter users in the world.

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The Vatican has told O’Loughlin that some of Francis’ most popular tweets can be seen by more than 20 million users. 

Francis signs off on everything, but there are a couple of layers of bureaucracy involved in the pope’s Twitter operation, which is housed in the Vatican’s office of the Secretary of State.

“It’s not just from a PR team,” O’Loughlin said. “The fact they have it housed in the Secretary of State's office shows they take it seriously as a diplomatic tool."

And while he tends not to tweet while traveling, O’Laughlin said the Vatican closely monitors social media and takes that information into account when it tailors its message to a host country’s sensibilities. 

“The Vatican has noticed that in the U.S. and U.K., people are upset at the church sex abuse scandal,” O’Loughlin said. In contrast, the faithful in Spain and Italy are much more concerned over the church’s extravagance and opulence. 

And so, while the action on social media surrounding the papal visit turned out to be the faithful talking among themselves, that doesn’t mean there isn’t an impact.

Just don’t expect Pope Francis to respond to tweets.  

He’s never done it, O’Loughlin said.