Lumen Gentium is a key document from the Second Vatican Council, which took place from 1962 to 1965. It is known as the "Dogmatic Constitution on the Church" and outlines the nature, mission, and structure of the Catholic Church. The document emphasizes the Church's role in the world and its relationship with all people, highlighting the importance of community and the call to holiness. The text also discusses the concept of the People of God, emphasizing that all members of the Church, including the laity, have a role in its mission. It promotes the idea of unity among Christians and encourages dialogue with other faiths, reflecting the Church's commitment to ecumenism and interfaith relations.