Sacrosanctum Concilium is the Constitution on the Sacred Liturgy, one of the key documents produced by the Second Vatican Council in 1963. It emphasizes the importance of the liturgy in the life of the Church and encourages active participation by the faithful. The document aims to promote a deeper understanding of the sacred rites and their significance in worship. The document also calls for reforms in the liturgy to make it more accessible and meaningful. It encourages the use of the vernacular language in the Mass, allowing congregations to engage more fully in the worship experience.