Originally named after Pope Gregory I (ca. 540-604) who organized and classified a sizable number of chants, the Gregorian chant (or plainchant) is a significant advancement of music in the Middle Ages as notation of the notes and the lyrics rose in importance. A chant was a piece of music sung with the text of a prayer and was an essential facet of the Mass. Plainchant is found in the Ordinary Mass which is separated into five parts: Kyrie, Gloria, Credo, Sanctus, and Agnus Dei.
Chants can have different "text settings," a word defined as "the relationship between the notes and the words." (Linda Sheppard, Early Music, ca. 600-1825). In a syllabic text setting, a single syllable of the text corresponds to each note of the music. A neumatic type of chant pairs one syllable with two to four notes. Finally, a melismatic style is described as words being extended over a succession of notes. Chants can also consist of only one line of melody with no harmony or accompaniment, having a monophonic texture. Another type of music consisting of a melody with an accompaniment has a homophonic texture. Lastly, a polyphonic texture refers to two or more musical lines independent from one another.
Notation of music emerged close to the year 900 and eventually progressed to a system that employed neumes, a term for "notes that are sung on a single pitch" (Linda Sheppard, Early Music, ca. 600-1825). The neumes signified a few aspects of the music:the relationship of the neumes to the text, some indication of the length, and the music's direction. Vertical lines give a short break for the singer to take a breath and also indicate the separation of musical phrases.
In Solesmes, the monastic custom was brought back to life by Dom Prosper Gueranger. After much research, the first book in the planned collection of chants was released, the Paleographie Musicale. A reprinting of the old Medicea version was created about eighteen years before and was deemed by Pope Pius IX the only legitimate edition. The Solesmes monks reconfigured the chant, attempting to do away with the polluted reprint of the Medicea edition. Having previously faced rejection, the Solesmes chant, which is today in a collection called Liber Usualis, finally was received by Pope Pius X and considered authoritative.