Ecclesiology is the theological study of the Church, focusing on her essence, mission, ministry, and worship practices. It delves into key aspects such as the Church's identity as the Body of Christ, her role in salvation history, and her relationship to Jesus, often described in scriptural terms as the bride and groom.

Central to Catholic ecclesiology are the sacraments, particularly water baptism and the Eucharist, which signify the initiation and nourishment of believers in their faith journey. The study of ecclesiology not only addresses the origins and foundational beliefs of the Church but also explores its governance structures (polity), disciplinary measures, and eschatological significance—how the Church prepares its members for the ultimate fulfillment in the Kingdom of God.

Additionally, ecclesiology examines the various forms of Church leadership and their responsibilities in guiding the faithful, promoting community, and advocating for the teachings of Christ. This multifaceted approach provides insights into how ecclesial communities engage with the world and fulfill their divine mission.

DOGMATIC CONSTITUTION ON THE CHURCH
LUMEN GENTIUM
SOLEMNLY PROMULGATED BY HIS HOLINESS
POPE PAUL VI
ON NOVEMBER 21, 1964

https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html