The Feast of the Immaculate Conception celebrates the Immaculate Conception of the Blessed Virgin Mary. It is celebrated on 8 December.

The doctrine of the day teaches that Virgin Mary, the mother of Christ, was conceived without sin and her conception was thus immaculate.

Jesus was miraculously conceived inside Mary, who was a virgin at the time. That is the Biblical concept of the virgin birth.

The doctrine of the Immaculate Conception was proclaimed as infallible by Pope Pius IX in the bull Ineffabilis Deus in 1854.

While the Eastern Orthodox Churches have never accepted the Roman Catholic dogma of the day, they do celebrate December 9 as the Feast of the Conception by St. Anne of the Most Holy Theotokos.

It is a public holiday in Andorra, Argentina, Austria, Chile, Colombia, Costa Rica, East Timor, Italy, Liechtenstein, Macau, Malta, Monaco, Nicaragua, Peru, Portugal, San Marino, Seychelles, Spain, Vatican City, Venezuela.