Alleluia () is a phrase in Christianity used to give praise to God. In Christian worship, Alleluia is used as a liturgical chant in which that word is combined with verses of scripture, usually from the Psalms. This chant is commonly used before the proclamation of the Gospel. In Western Christianity, congregations commonly cease using the word Alleluia during the period of Lent but restore it into their services at Easter. The form of praise "Alleluia" is used by Christians to thank and glorify God; it finds itself present in many prayers and hymns, especially those related to Eastertide, such as "Jesus Christ Is Risen Today".
The Hebrew word Hallelujah as an expression of praise to God was preserved, untranslated, by the Early Christians as a superlative expression of thanksgiving, joy, and triumph. Thus it appears in the ancient Greek Liturgy of St. James, which is still used to this day by the Patriarch of Jerusalem and, in its Syriac recension is the prototype of that used by the Maronites. In the Liturgy of St. Mark, apparently the most ancient of all, we find this rubric: "Then follow let us attend, the Apostle, and the Prologue of the Alleluia." The "Apostle" is the usual ancient Eastern title for the Epistle reading, and the "Prologue of the Alleluia" would seem to be a prayer or verse before Alleluia was sung by the choir. It has been suggested that the acclamation arises from and is an onomatopoeic rendition of the ancient tradition of ululation.
In the Eastern Orthodox, as well as Byzantine Rite Eastern Catholic and Eastern Lutheran Churches, after reading the Apostle (Epistle) at the Divine Liturgy, the Reader announces which of the Eight Tones the Alleluia is to be chanted in. The response of the choir is always the same: "Alleluia, alleluia, alleluia." What differs is the tone in which it is sung, and the stichera (psalm verses) which are intoned by the Reader.
The Alleluia is paired with the Prokeimenon which preceded the reading of the Apostle.