We often hear Catholics talk about Vatican II.
Vatican II, known as The Second Ecumenical Council of the Vatican and/or the Second Vatican Council, was called by St. Pope John XXIII on October 11, 1962. This Council was the first in more than 100 years. So many events had taken place during this 100 year period, to name a few: World War I, the Spanish Flu pandemic, World War II, Korean War, Vatican II ended under St. Pope Paul VI on December 8, 1965. The Council addressed the relationships between the Church and the world. Some of the participants included 2 of our most recent popes: St. John Paul II and Pope Emeritus Benedict XVI.