pope francis
Twitter created four custom emoji ahead of the pope's first visit to the United States. Twitter users must type particular hashtags to see them appear. Getty Images

The pope is coming, and Twitter knows just how to celebrate. The microblogging site created four custom emoji to correspond with hashtags about Pope Francis's visit to the United States this week.

When a Twitter user types #PopeInUS, a man's head topped with gray hair (evidently symbolizing Pope Francis himself) and placed on top of the American flag appears. An emoji for the Statue of Liberty corresponds with #PopeInNYC, a White House emoji for #PopeInDC and a Liberty Bell emoji for #PopeInPhilly. Twitter employee Bridget Coyne showed off each of these hashtags in a post of the social network Monday evening.

Twitter has been growing its practice of making custom emoji. The network has often created emoji for special events, such as an astronaut for MTV's Video Music Awards and Star Wars characters to celebrate the release of the upcoming movie. When the Supreme Court passed the same-sex marriage ruling in June, Twitter created a rainbow heart emoji to appear alongside #LoveWins, which was tweeted by U.S. President Barack Obama shortly after the decision was announced and quickly began trending.

These hashtags typically draw excitement from Twitter's community of 330 active monthly users. The #LoveWins hashtag drew 11 million mentions before the heart was taken down. Most of these emoji disappear shortly after the event is over. The emoji are retroactively placed alongside hashtags regardless of whether it was posted before or after they were released.

Last week, Twitter began experimenting with brand-sponsored emoji, in a first collaboration with Coke. An image of two glass bottles of Coke clinking appeared next to #ShareACoke. Twitter declined to reveal details on the revenue deal and wass unclear about the future of the product in an interview with TechCrunch.

"Coca-Cola is a massive global partner of Twitter, and they have been pushing us for some time on building a custom emoji (along with the creative agency W+K)," Twitter's senior director of global brand strategy, Ross Hoffman, told TechCrunch. "We know that people love using [emoji], and usage has been significantly increasing over time on our platform."

What gives with emoji? As Hoffman notes, Twitter users seem to love them. Brands have been adding them to their messaging, such as celebrating World Emoji Day this year. Even Washington politicians have embraced them. Democratic presidential contender Hillary Clinton asked constituents to explain what the student debt crisis meant to them with three emoji in August.

It's also become popular for brands and organizations to create their own custom emoji, beyond Twitter, as was also done for the pope.

For Twitter, emoji go beyond having 140 text characters to work with, adding to Twitter’s visual focus. It is unclear how long the pope emoji will be available on Twitter. The pope’s official Twitter account (@Pontifex) was created in February 2012, despite Pope Francis repeatedly coming out against technology. He has yet to use the new emoji.