The Holy See (Latin: Sancta Sedes, Italian: Santa Sede) refers to the episcopal jurisdiction of the Catholic Church in Rome. The primacy of Rome makes its bishop the worldwide leader of the church, commonly known as the Pope. Since Rome is the preeminent episcopal see of the church, it contains the central government of the church, including various agencies essential to administration. As such, diplomatically, the Holy See acts and speaks for the whole Catholic Church. It is also recognized by other subjects of international law as a sovereign entity, headed by the Pope, with which diplomatic relations can be maintained."

Although it is often referred to as "the Vatican", the Holy See is not the same entity as the Vatican City State, which came into existence only in 1929; the Holy See, the episcopal see of Rome, dates back to early Christian times. Ambassadors are officially accredited not to the Vatican City State but to "the Holy See", and papal representatives to states and international organizations are recognized as representing the Holy See, not the Vatican City State.

Holiness, or sanctity, is in general the state of being holy (perceived by religious individuals as associated with the divine) or sacred (considered worthy of spiritual respect or devotion; or inspiring awe or reverence among believers in a given set of spiritual ideas). In other contexts, objects are often considered 'holy' or 'sacred' if used for spiritual purposes, such as the worship or service of gods. These terms can also be used in a non-spiritual or semi-spiritual context ("sacred truths" in a constitution). It is often ascribed to people ("a holy man" of religious occupation, "holy prophet" who is venerated by his followers), objects ("sacred artifact" that is venerated and blessed ), times ("holy days" of spiritual introspection, such as during winter holidays), or places ("sacred ground", "holy place").

The word "sacred" descends from the Latin sacrum, which referred to the gods or anything in their power, and to sacerdos, priest; sanctum, set apart. It was generally conceived spatially, as referring to the area around a temple.