Common practice period in the context of "Atonality"

In a musical composition, a chord progression or harmonic progression (informally chord changes, used as a plural, or simply changes) is a succession of chords. Chord progressions are the foundation of harmony in Western musical tradition from the common practice era of classical music to the 21st century. Chord progressions are the foundation of popular music styles (e.g., pop music, rock music), traditional music, as well as genres such as blues and jazz. In these genres, chord progressions are the defining feature on which melody and rhythm are built.

In tonal music, chord progressions have the function of either establishing or otherwise contradicting a tonality, the technical name for what is commonly understood as the "key" of a song or piece. Chord progressions, such as the extremely common chord progression I-V-vi-IV, are usually expressed by Roman numerals in classical music theory. In many styles of popular and traditional music, chord progressions are expressed using the name and "quality" of the chords. For example, the previously mentioned chord progression, in the key of E♭ major, would be written as E♭ major–B♭ major–C minor–A♭ major in a fake book or lead sheet. In the first chord, E♭ major, the "E♭" indicates that the chord is built on the root note "E♭" and the word "major" indicates that a major chord is built on this "E♭" note.

Medieval music encompasses the sacred and secular music of Western Europe during the Middle Ages, from approximately the 6th to 15th centuries. It is the first and longest major era of Western classical music and is followed by the Renaissance music; the two eras comprise what musicologists generally term as early music, preceding the common practice period. Following the traditional division of the Middle Ages, medieval music can be divided into Early (500–1000), High (1000–1300), and Late (1300–1400) medieval music.

Medieval music includes liturgical music used for the church, other sacred music, and secular or non-religious music. Much medieval music is purely vocal music, such as Gregorian chant. Other music used only instruments or both voices and instruments (typically with the instruments accompanying the voices).

Baroque music (UK: /bəˈrɒk/ or US: /bəˈroʊk/) refers to the period or dominant style of Western classical music composed from about 1600 to 1750. The Baroque style followed the Renaissance period, and was followed in turn by the Classical period after a short transition (the galant style). The Baroque period is divided into three major phases: early, middle, and late. Overlapping in time, they are conventionally dated from 1580 to 1650, from 1630 to 1700, and from 1680 to 1750. Baroque music forms a major portion of the "classical music" canon, and continues to be widely studied, performed, and listened to. The term "baroque" comes from the Portuguese word barroco, meaning "misshapen pearl". Key composers of the Baroque era include Johann Sebastian Bach, George Frideric Handel, Henry Purcell, Antonio Vivaldi, Georg Philipp Telemann, Domenico Scarlatti, Claudio Monteverdi, Girolamo Frescobaldi, Alessandro Scarlatti, Jean-Baptiste Lully, Jean-Philippe Rameau, Arcangelo Corelli, François Couperin, Heinrich Schütz, Dieterich Buxtehude, and Heinrich Ignaz Franz Biber.

The Baroque saw the formalization of common-practice tonality, an approach to writing music in which a song or piece is written in a particular key; this type of harmony has continued to be used extensively in Western classical and popular music. During the Baroque era, professional musicians were expected to be accomplished improvisers of both solo melodic lines and accompaniment parts. Baroque concerts were typically accompanied by a basso continuo group (comprising chord-playing instrumentalists such as harpsichordists and lute players improvising chords from a figured bass part) while a group of bass instruments—viol, cello, double bass—played the bassline. A characteristic Baroque form was the dance suite. While the pieces in a dance suite were inspired by actual dance music, dance suites were designed purely for listening, not for accompanying dancers.

The Symphony No. 9 in D minor, Op. 125, is a choral symphony, the final complete symphony by Ludwig van Beethoven, composed between 1822 and 1824. It was first performed in Vienna on 7 May 1824. The symphony is regarded by many critics and musicologists as a masterpiece of Western classical music and one of the supreme achievements in the history of music. One of the best-known works in common practice music, it stands as one of the most frequently performed symphonies in the world.

The Ninth was the first example of a major composer scoring vocal parts in a symphony. The final (4th) movement of the symphony, commonly known as the Ode to Joy, features four vocal soloists and a chorus in the parallel key of D major. The text was adapted from the "An die Freude (Ode to Joy)", a poem written by Friedrich Schiller in 1785 and revised in 1803, with additional text written by Beethoven. In the 20th century, an instrumental arrangement of the chorus was adopted by the Council of Europe, and later the European Union, as the Anthem of Europe.

Diatonic and chromatic are terms in music theory that are used to characterize scales. The terms are also applied to musical instruments, intervals, chords, notes, musical styles, and kinds of harmony. They are very often used as a pair, especially when applied to contrasting features of the common practice music of the period 1600–1900.

These terms may mean different things in different contexts. Very often, diatonic refers to musical elements derived from the modes and transpositions of the "white note scale" C–D–E–F–G–A–B. In some usages it includes all forms of heptatonic scale that are in common use in Western music (the major, and all forms of the minor).

Voice leading (or part writing) is the linear progression of individual melodic lines (voices or parts) and their interaction with one another to create harmonies, typically in accordance with the principles of common-practice harmony and counterpoint. These principles include voices sounding smooth and independent, generally minimising movement to common tones as well as steps to the closest chord tone possible, therefore minimising leaps where possible. As a result, different voicings and inversions of chords may provide smoother voice leading.

Rigorous concern for voice leading is of greatest importance in common-practice music, although jazz and pop music also demonstrate attention to voice leading to varying degrees.

In the music theory of harmony, the root is a specific note that names and typifies a given chord. Chords are often spoken about in terms of their root, their quality, and their extensions. When a chord is named without reference to quality, it is assumed to be major—for example, a "C chord" refers to a C major triad, containing the notes C, E, and G. In a given harmonic context, the root of a chord need not be in the bass position, as chords may be inverted while retaining the same name, and therefore the same root.

In tertian harmonic theory, wherein chords can be considered stacks of third intervals (e.g. in common practice tonality), the root of a chord is the note on which the subsequent thirds are stacked. For instance, the root of a triad such as E Minor is E, independently of the vertical order in which the three notes (E, G and B) are presented. A triad can be in three possible positions, a "root position" with the root in the bass (i.e., with the root as the lowest note, thus E, G, B or E, B, G from lowest to highest notes), a first inversion, e.g. G, B, E or G, E, B (i.e., with the note which is a third interval above the root, G, as the lowest note) and a second inversion, e.g. B, E, G or B, G, E, in which the note that is a fifth interval above the root (B) is the lowest note.