Pope Benedict XVI announced Monday morning that he plans to retire effective at 8 p.m. Feb. 28, making him the first pope to resign since 1415.

The 85-year-old pope cited age and declining health in his address, which was made in Latin, to cardinals in Vatican City.

USA Today reports that he 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' for the task."

He went on to say, "Both strength of mind and body are necessary strengths, which in the last few months have deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me."

Follow this next link to see the full transcript.

Elisabetta Povoledo of The New York Times writes that, "In recent months, Benedict had been showing signs of age. He often seemed tired and even appeared to doze off during Midnight Mass on Christmas Eve, after being brought to the altar of Saint Peter’s on a wheeled platform. But few expected the pope to resign so suddenly, even though he had said in the past that he would consider the option."

The news has indeed sent shock waves around the world and is leading to discussions about why, what's next and how things will proceed.

TIME outlined parts of the process and some of the rules:

— Cardinals from around the world will head to Rome to take part in a procedure known as a conclave. The group, known as the College of Cardinals, will stay in the Casa di Santa Marta—a $20-million hotel-style residence inside the Vatican walls—and won’t leave the Vatican grounds until the new pope has been selected.

—All electors must be under the age of 80, leaving 118 cardinals eligible to take part out of a total of 210.

— The conclave will take place behind closed doors in the Vatican’s famous Sistine Chapel.

— The first ballot may be held on the first afternoon of the conclave, after morning Mass. After that, the conclave will hold two ballots in the morning and two ballots in the afternoon until a pope is elected.

— After each voting round, tradition dictates that the ballots are bound together and burned in a special oven erected temporarily inside the chapel. The smoke rising from the Sistine Chapel’s chimney signals to the expectant faithful in St. Peter’s Square the outcome of the vote.

— If the smoke is black (an effect produced by a chemical compound burned along with the ballots), it means that no candidate has achieved the two-thirds majority needed to win – and another round of balloting will take place. If the smoke is white, a new pope has been elected.

— A senior cardinal then takes to the balcony of St. Peter’s Basilica to announce, in Latin: “Annuntio vobis gaudium magnum. Habemus papam.” Which translates as, “I announce to you news of great joy. We have a pope.”

Benedict XVI chose his name in honor of Pope Benedict XV, who was pope during WWI. He also wanted to model his papacy after the sixth-century monastic leader, St. Benedict.

The former Cardinal Joseph Ratzinger was elected as pope on April 19, 2005. At the time of his election, Benedict was popular within the college of 115 cardinals who chose him along with his conservative theology that mirrored his predecessor, John Paul.

Benedict was clouded by controversy at times, however. Reuters reports that, "The Church has been rocked during Benedict's nearly eight-year papacy by child sexual abuse crises and Muslim anger after the pope compared Islam to violence. Jews were upset over rehabilitation of a Holocaust denier and there was scandal over the leaking of the pope's private papers by his personal butler."

The pope also stepped up the church's protest to gay marriage, emphasized the Church's opposition to female priesthood and rejected research for embryonic stem cells.

Among other things Pope Benedict XVI will be remembered for is that he is the first pope to have his own Twitter handle.