In the liturgical calendar is it the memory at Adam and Eva (Paradies and case of sin) assigned. It is the last day of the Adventszeit and this very day in many places up to the nocturnal Weihnachtsmesse (Mette) as a chamfering day is committed, but has itself the family Weihnachtsfeier with giving and Festessen in Europe more and more on thatEvening or already the afternoon before-before. Kirchlicherseits and outside of Europe becomes against it further the 25. December as Weihnachtstag committed.
Also the service time was continued to prefer by the midnight ever into the evening hours. At sunset in the late afternoon “Kinderchristmetten” and “crib plays” in many places already take place.The actual Christmette may not begin in accordance with the renewed liturgical regulations of the catholic church however before 22 o'clock, since it concerns a night celebration, because Christ was born at night after information of the new will. After antique calendar the new day begins already the previous evening,therefore the nocturnal celebration already belongs to the following Weihnachtstag and no longer to the holy evening.
|Wiktionary: Christmas eve - word origin, synonyms and translations|