Plainsong in the context of "Gallican chant"

Gregorian chant is the central tradition of Western plainchant, a form of monophonic, unaccompanied sacred song in Latin (and occasionally Greek) of the Roman Catholic Church. Gregorian chant developed mainly in western and central Europe during the 9th and 10th centuries, with later additions and redactions. Although popular legend credits Pope Gregory I with inventing Gregorian chant, scholars believe that he only ordered a compilation of melodies throughout the whole Christian world, after having instructed his emissaries in the Schola Cantorum, where the neumatical notation was perfected, with the result of most of those melodies being a later Carolingian synthesis of the Old Roman chant and Gallican chant.

Gregorian chants were organized initially into four, then eight, and finally 12 modes. Typical melodic features include a characteristic ambitus, and also characteristic intervallic patterns relative to a referential mode final, incipits and cadences, the use of reciting tones at a particular distance from the final, around which the other notes of the melody revolve, and a vocabulary of musical motifs woven together through a process called centonization to create families of related chants. The scale patterns are organized against a background pattern formed of conjunct and disjunct tetrachords, producing a larger pitch system called the gamut. The chants can be sung by using six-note patterns called hexachords. Gregorian melodies are traditionally written using neumes, an early form of musical notation from which the modern four-line and five-line staff developed. Multi-voice elaborations of Gregorian chant, known as organum, were an early stage in the development of Western polyphony.

Old Roman chant is the liturgical plainchant repertory of the Roman rite of the early Christian Church. It was formerly performed in Rome, and, although it is closely related to Gregorian chant, the two are distinct. Unlike other chant traditions (such as Ambrosian chant, Mozarabic chant, and Gallican chant), Old Roman chant and Gregorian chant share essentially the same liturgy and the same texts. Many of their melodies are also closely related. Although primarily associated with the churches of Rome, the Old Roman chant was also performed in parts of central Italy, and it was possibly performed much more widely. Gregorian Chant gradually but completely supplanted Old Roman Chant between the 11th century and the 13th century AD.

Ambrosian chant (also known as Milanese chant) is the liturgical plainchant repertory of the Ambrosian rite of the Roman Catholic Church, distinct from the more widely known Gregorian chant. It is primarily associated with the Archdiocese of Milan, and named after St. Ambrose much as Gregorian chant is named after Gregory the Great. It is the only surviving plainchant tradition besides the Gregorian to maintain the official sanction of the Roman Catholic Church.

Beneventan chant is a liturgical plainchant repertory of the Roman Catholic Church, used primarily in the orbit of the southern Italian ecclesiastical centers of Benevento and Monte Cassino distinct from Gregorian chant and related to Ambrosian chant. It was officially supplanted by the Gregorian chant of the Roman rite in the 11th century, although a few Beneventan chants of local interest remained in use.

Mozarabic chant (also known as the Hispanic chant, Old Hispanic chant, Old Spanish chant, or Visigothic chant) is the liturgical plainchant repertory of the Visigothic/Mozarabic rite of the Catholic Church, related to the Gregorian chant. It is primarily associated with Hispania under Visigothic rule and later with the Mozarabs (Hispanic Catholic Christians living under Islamic rule and speaking Arabic) and was replaced by the chant of the Roman rite following the Christian Reconquest of the Iberian Peninsula. Although its original medieval form is largely lost, a few chants have survived with readable musical notation, and the chanted rite was later revived in altered form and continues to be used in a few isolated locations in Spain, primarily in Toledo.

In Christian music, a Passion is a setting of the Passion of Christ. Liturgically, most Passions were intended to be performed as part of church services in the Holy Week.

Passion settings developed from medieval intoned readings of the Gospel texts relating Christ's Passion, to which later polyphonic settings were added. Passion Plays, another tradition that originated in the Middle Ages, could be provided with music such as hymns, contributing to Passion as a genre in music.