The Second Vatican Council was a major ecumenical council of the Catholic Church held in Vatican City from 1962 to 1965.

It was convened by Pope John XXIII and was a landmark event in the modern history of the Catholic Church.

The purpose of the council was 'aggiornamento,' an Italian word meaning 'updating' or 'bringing up to date.'

It was not convened to condemn heresies, but to renew the Church and engage with the modern world.

One of the most visible changes was the reform of the liturgy, which allowed Mass to be celebrated in local languages rather than exclusively in Latin.

The council placed a new emphasis on the role of the laity (non-clergy) as active participants in the life of the Church.

It promoted ecumenism, encouraging dialogue and better relations with other Christian denominations.

The declaration 'Nostra aetate' was a groundbreaking document that repudiated anti-Semitism and transformed the Church's relationship with Judaism and other non-Christian religions.

The council also issued a declaration on religious freedom, affirming it as a fundamental human right.

Vatican II initiated the most significant changes in the Catholic Church in centuries.