Responsorial psalmody primarily refers to the placement and use of the Psalm within the readings at a Christian service of the Eucharist.
They are found in the liturgies of several Christian denominations, including those of Roman Catholicism, Lutheranism and Anglicanism.
The "responsorial" aspect is used in two related but different ways: the liturgical position of the psalm as a 'response' to the first (Old Testament) reading, and one possible manner of reciting it.
In this moment the cantor leads the faithful praying to God, and even the priest or bishop celebrating responds: together all of us gathered in worship praise God through the psalm, and we become the chorus of that prayer through reciting or singing the refrain.
Fathers of the Church mentioning this format include Augustine, John Chrysostom and Leo the Great.
[5] Originally the deacon was the singer of this psalm and versicle; over time the role moved to the subdeacon then to the choir.
[5] More usually, the term refers to an antiphonal manner of reciting the psalm, with a choir or cantor and to which the congregation interjects a periodic 'response'.