Pythagorean music theory was developed by the Greek philosopher Pythagoras in the 6th century BC. It is based on the idea that music is a mathematical phenomenon and that the intervals between notes can be expressed as ratios of whole numbers.

Guido of Arezzo was an Italian Benedictine monk who lived in the 11th century. He is credited with developing the first system of musical notation, which used letters to represent different pitches.

Staff notation is a system of musical notation that uses a staff, which is a set of five horizontal lines, to represent the pitch of notes. Notes are placed on the staff according to their pitch, with higher notes being placed higher on the staff and lower notes being placed lower on the staff.

Equal temperament is a system of musical tuning in which the intervals between notes are all equal. This means that all of the notes in a scale sound equally in tune with each other. Equal temperament is the most common system of tuning used today.

Harmonic theory is a theory of music that deals with the relationships between chords. Rameau's harmonic theory was based on the idea that chords are built on a foundation of triads, which are three-note chords that consist of a root, a third, and a fifth.

Schenkerian analysis is a theory of music that deals with the structure of musical compositions. Schenker's theory is based on the idea that all musical compositions can be reduced to a series of underlying harmonic progressions.

The twelve-tone technique is a method of musical composition that uses all twelve notes of the chromatic scale equally. Schoenberg developed the twelve-tone technique in order to create a new system of musical composition that was not based on traditional tonality.

Total serialism is a method of musical composition that uses all of the elements of music, including pitch, rhythm, dynamics, and timbre, as a series. Boulez developed total serialism in order to create a new system of musical composition that was even more radical than Schoenberg's twelve-tone technique.

Electronic music is a type of music that is created using electronic instruments, such as synthesizers and computers. Stockhausen was one of the pioneers of electronic music, and he developed a number of new techniques for creating electronic music.

Indeterminacy is a theory of music that emphasizes the role of chance and improvisation in musical composition. Cage developed indeterminacy in order to create a new system of musical composition that was not based on traditional notions of melody, harmony, and rhythm.

Serialism is a method of musical composition that uses a series of pitches, rhythms, or other musical elements as the basis for a composition. Babbitt developed serialism in order to create a new system of musical composition that was based on mathematical principles.

The twelve-tone technique is a method of musical composition that uses all twelve notes of the chromatic scale equally. Perle developed a new approach to the twelve-tone technique that allowed him to create music that was more expressive and lyrical than Schoenberg's music.

Serialism is a method of musical composition that uses a series of pitches, rhythms, or other musical elements as the basis for a composition. Carter developed a new approach to serialism that allowed him to create music that was more complex and challenging than Babbitt's music.

Electronic music is a type of music that is created using electronic instruments, such as synthesizers and computers. Berio was one of the pioneers of electronic music, and he developed a number of new techniques for creating electronic music.

Electronic music is a type of music that is created using electronic instruments, such as synthesizers and computers. Stockhausen was one of the pioneers of electronic music, and he developed a number of new techniques for creating electronic music.