Pope Francis announced the start of a Year of Prayer on Sunday in preparation for the Catholic Church’s 2025 Jubilee Year.

In his Angelus address, the pope said that a Year of Prayer starting on Jan. 21 will be “a year dedicated to rediscovering the great value and absolute need for prayer in one’s personal life, in the life of the Church, and in the world.”

“Dear brothers and sisters, the coming months will lead us to the opening of the Holy Door, with which we will begin the jubilee,” Pope Francis said from the window of the Apostolic Palace.

“I ask you to intensify your prayer to prepare us to live this event of grace well and to experience the power of God’s hope. That is why today we begin a Year of Prayer.”

The pope said that the Vatican’s Dicastery for Evangelization will publish resources to help Catholic communities to more fully participate in the Year of Prayer. The Holy See Press Office has also announced that a press conference on the Year of Prayer will take place on Jan. 23.

The Vatican and the city of Rome are expecting an estimated 35 million people to flock to the Eternal City for the 2025 Jubilee Year of Hope — the first ordinary jubilee since the Great Jubilee of 2000.

A jubilee is a special holy year of grace and pilgrimage in the Catholic Church. It typically takes place once every 25 years, though the pope can call for extraordinary jubilee years more often, such as in the case of the 2016 Year of Mercy or the 2013 Year of Faith.

Jubilees have biblical roots. The Book of Leviticus called for jubilee years to be held every 50 years for the freeing of slaves and forgiveness of debts as manifestations of God’s mercy. The practice was reestablished by Pope Boniface VIII in 1300.

The 2025 Jubilee Year begins on Dec. 24, 2024 (Christmas Eve), and concludes on Jan. 6, 2026.

The Holy Doors are a central part of any jubilee. These doors, found at St. Peter’s Basilica and Rome’s other major basilicas, are sealed from the inside and opened during a jubilee year.

The opening of the Holy Door symbolizes the offering of an “extraordinary path” toward salvation for Catholics during a jubilee. Pilgrims who walk through a Holy Door can receive a plenary indulgence under the usual conditions.

Pope Francis announced the Year of Prayer from the window of the Apostolic Palace after presiding over Mass in St. Peter’s Basilica for the Sunday of the Word of God.

In his reflection on Sunday’s Gospel in his Angelus address, Pope Francis said that “the Lord loves to involve us in his work of salvation.”

“Bringing God’s salvation to everyone was for Jesus the greatest joy, his mission, the meaning of his existence … And in every word and deed with which we join with him in the beautiful adventure of giving love, light, and joy multiply not only around us but also within us”, he said.

This story was previously published on CNA.