His Holiness is a style and form of address (in the variant form Your Holiness) for some supreme religious leaders. The title is most notably used by the pope, Oriental Orthodox patriarchs or Catholicoi, and Dalai Lama.
The full papal title, rarely used, is:
The best-known title, that of "Pope", does not appear in the official list of titles, but is commonly used in the titles of documents, and appears, in abbreviated form, in their signatures as "PP." standing for Papa (Pope). The 2020 Annuario Pontificio lists all of his formal titles, except Bishop of Rome, as "historical titles."
It is customary when referring to popes to translate the regnal name into local languages. Thus he is Papa Franciscus in Latin (the official language of the Holy See), Papa Francesco in Italian (the language of the Vatican), Papa Francisco in his native Spanish, and Pope Francis in English.
The term is sometimes abbreviated to "HH" or "H.H." when confusion with "His/Her Highness" is unlikely. The associated form of address is "Your Holiness".
His Holiness (Latin: Sanctitas) is the official style also used to address the Oriental Orthodox Catholicoi/patriarchs. In the Eastern Orthodox Church, the ecumenical patriarch of Constantinople has the title of His All-Holiness (abbreviation HAH). It is also used for certain other Eastern patriarchs, notably those who head a church or rite which recognizes neither Rome's nor Constantinople's primacy.
The English language honorific "His Holiness", and as female version "Her Holiness", has commonly been used for religious leaders from other traditions, including Buddhism (for figures such as Lu Sheng-yen, the Dalai Lama, the Karmapa, and the Je Khenpo in Bhutan), Shinto in Ahmadiyya Islam for the Caliph and in Dawoodi Bohra sect of Ismaili Shia for esteemed office of Da'i al-Mutlaq, Syedna.