We Have a Pope is the announcement given in Latin by the senior Cardinal Deacon – the Cardinal Proto-Deacon – upon the election of a new pope.
The announcement is given from the central balcony of St. Peter’s Basilica in the Vatican. After the announcement, the new pope is presented to the people and he gives his first Urbi et Orbi blessing.
The format for the announcement when a cardinal is elected Pope is:
Annuntio vobis gaudium magnum:
Eminentissimum ac reverendissimum Dominum,
Dominum [First Name],
Sanctæ Romanæ Ecclesiæ Cardinalem [Last Name],
Qui sibi nomen imposuit [Papal Name].
In English, it reads:
I announce to you a great joy:
We have a Pope!
The most eminent and most reverend Lord,
Lord [First Name],
Cardinal of the Holy Roman Church [Last Name],
Who takes to himself the name of [Papal Name].
A 15th century depiction of the calling of the Habemus Papam
In announcing the name of the newly-elected pontiff, the new pontiff’s birth forename or first name is announced in Latin in the accusative case (e.g. Angelum Iosephum, Ioannem Baptistam, Albinum, Carolum, Iosephum), but the new pontiff’s surname or family name is given in the original form (e.g. Roncalli, Montini, Luciani, Wojtyła, Ratzinger).
The new pope’s regal name is usually given in the genitive case in Latin (e.g. Ioannis vicesimi tertii, Ioannis Pauli primi etcetera), although it can also be declined in the accusative case in Latin – as was the case in 1963 when Pope Paul VI’s regal name was announced as Paulum sextum.