The Holy See, or the Vatican as it is sometimes known, is the 'seat of government' of the universal Catholic Church.
It is the seat of the Bishop of Rome – the Pope – who “as pastor of the entire Church, has full, supreme and universal power over the whole Church, a power which he can always exercise unhindered.” Lumen Gentium, Dogmatic Constitution of the Church, 22.
Geographically it is located in the Diocese of Rome in Vatican City. In terms of governance, overall responsibility rests with the Holy Father and by extension the Curia, which consists of the Secretariat of State, the Council for Public Affairs of the Church, the Sacred Congregations, tribunals, and other institutions and offices (Code of Canon Law, #360).
It is a sovereign entity of international law.
Vatican News is the Holy See's news and information portal that provides information on the activities of the Pope, the Vatican, local Churches and world news updates.
The Second Ecumenical Vatican Council was a universal meeting of bishops in Rome that met for four consecutive autumns between 1962-65.