Pope Benedict XVI surprised the world on Monday when he announced his resignation from the papacy.

In a speech on Monday, Pope Benedict said: 

"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. ... In today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me. For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005 ..."

Pope Benedict will leave his post as leader of the Roman Catholic Church on Feb. 28. He is the first pope to resign since Pope Gregory XII in 1415. 

News of the resignation sparked a flurry of statements from world leaders—from world leaders such as U.K. Prime Minister David Cameron to Catholic bishops worldwide—as well as an avalanche of tweets. Twitter's trending topics list on Twitter included various terms related to the resignation: #Pope, Feb. 28, and Vatican. The reactions online range from shock to that of humor and irreverence.  

The Vatican modernized its communications to the public during Benedict's papacy, embracing social media as a form of outreach. Pope Benedict, who has 1.5 million followers on Twitter, has not tweeted about his resignation yet.