Chord (music)

{{Short description|Harmonic grouping of notes}} {{Redirect|Chording|the computer input method|Chorded keyboard}} {{Redirect|Akkord|the corp|Akkord Industry Construction Investment Corporation}}

thumb|A C major chord. A '''chord''' is the simultaneous sound of two or more musical notes. The most common chord has three notes and is known as a triad. Added tone chords, extended chords, and tone clusters can have more than three notes and are common in contemporary classical music and jazz.

An arpeggio is a chord where notes are sounded separately. A series of chords is sometimes called a chord progression. There are several ways to notate chords including figured bass, Roman numerals, the Nashville Number System, and alphabetical chord notation.

==Definition== {{See also|Chord progression|Harmony|Homophony}} [[File:Mussorgsky - Pictures at an Exhibition - Promenade.svg|thumb|The "Promenade" in Modeste Mussorgsky's ''Pictures at an Exhibition'' demonstrates a simple homophonic texture.<ref name=Nattiez/>]] A chord is the sound of two or more notes being played at the same time.<ref name=GroveC>"[https://www.oxfordmusiconline.com/grovemusic/view/10.1093/gmo/9781561592630.001.0001/omo-9781561592630-e-0000005671 Chord]." ''Grove Music Online''. Oxford University Press, 2001.</ref><ref>Karolyi, Otto. ''[https://archive.org/details/introducingmusic0000unse/page/63/mode/1up Introducing Music]''. Penguin Books, 1965. 63–78.</ref> The term derives from "accord", which became "cord" in Middle English. The original meaning was an agreement or harmonious sound. In the 17th century, the spelling was changed to "chord" to prevent confusion with "cord".<ref>"[https://doi.org/10.1093/OED/2509732904 Chord, N. (2), Etymology.]" Oxford English Dictionary, Oxford University Press, March 2025.</ref><ref>"[https://www.merriam-webster.com/dictionary/chord Chord]." Merriam-Webster Dictionary. Accessed 20 Feb. 2026.</ref>

Until the Middle Ages, harmony was any combination of two notes. In the Renaissance, the simultaneous sound of three notes began to be understood as the working definition of harmony.<ref name=GroveH95/><ref>Jones, George T. ''HarperCollins College Outline Music Theory''. Wildside Press, LLC, 1994. 43.</ref><ref>Surmani, Andrew. ''Essentials of Music Theory: A Complete Self-Study Course for All Musicians''. Alfred Music, 2004. 72.</ref> An arpeggio is a broken chord where each note is sounded successively instead of simultaneously.<ref>Mason, William. ''[https://www.google.com/books/edition/A_system_of_technical_exercises_for_the/-90mFVLOkVwC?hl=en&gbpv=1&pg=PA73 A System of Technical Exercises for the Pianoforte]''. Oliver Ditson & Company, 1878. 73.</ref> Chords can also be implied by melodies.<ref name=Nattiez>Nattiez, Jean-Jacques. ''[https://archive.org/details/musicdiscourseto0000natt/page/218/mode/1up Music and Discourse: Toward a Semiology of Music]''. Translated by Carolyn Abbate. Princeton University Press, 1990. 218.</ref><ref>Trainor, Laurel J. and S.E. Trehub. "[https://trainorlab.mcmaster.ca/publications/pdfs/trainor_trehub_1994pdf.pdf Key membership and implied harmony in Western tonal music: developmental perspectives]", ''Perception and Psychophysics'', 56(2). 1994. 127f.</ref>

A chord progression is a collection of harmonies with a specific destination or purpose, such as reinforcing the tonic or modulation to a new pitch center.<ref>Schoenberg, Arnold. ''[https://archive.org/details/structuralfuncti0000arno_y8s5/page/1/mode/1up Structural Functions of Harmony]''. Norton, 1954.</ref>{{rp|1}} Chord progressions are common in Western music.<ref>Malm, William P. ''Music Cultures of the Pacific, the Near East, and Asia'' (3rd ed.). Prentice Hall, 1996. 15.</ref> Homophonic textures where the melody and harmony generally move in unison are considered the standard practice in classical music and remain central to music instruction.<ref>Hyer, Brian. "[https://www.oxfordmusiconline.com/grovemusic/view/10.1093/gmo/9781561592630.001.0001/omo-9781561592630-e-0000013291 Homophony]." ''Grove Music Online''. Oxford University Press, 2001.</ref> The study of harmony involves chords and progressions and the principles of connection that govern them.<ref name=GroveH95>Dahlhaus, Carl. "[https://archive.org/details/newgrovedictiona0008unse_x9z4/page/175/mode/1up Harmony]". In Sadie, Stanley; Tyrrell, John (eds.). ''The New Grove Dictionary of Music and Musicians'' London: Macmillan Publishers, 1995. 175.</ref>

== History == [[File:Einsiedeln MS Codex 79 (522) fol. 8v Musica enchiriadis - paralel Tu patris sempiternus es filius in Daseian notation.jpg|thumb|399x399px|A 9th century example of polyphony in parallel fifths from ''Musica enchiriadis'': ''Tu patris sempiternus es filius'' written in Daseian notation.<ref>''[https://archive.org/details/erickson-1995-musica-enchiriadis-and-scolica-enchiriadis/page/19/mode/1up Musica Enchiriadis and Scolica Enchiriadis]''. Translated by Raymond Erickson. Edited by Claude V. Palisca. Yale University Press, 1995. 19.</ref>]] Between the 16th and 18th centuries, chords developed into primary musical elements that were distinct from their polyphonic origins.<ref name=GroveH>Cohn, Richard, Brian Hyer, Carl Dahlhaus, Julian Anderson, and Charles Wilson. "[https://www.oxfordmusiconline.com/grovemusic/view/10.1093/gmo/9781561592630.001.0001/omo-9781561592630-e-0000050818 Harmony]." ''Grove Music Online''. Oxford University Press, 2001.</ref> In early church polyphony known as ''organum'', a plainsong was paired with another melody. This two-part counterpoint developed gradually into ever more complex polyphonic writing.<ref>Britannica Editors. "[https://www.britannica.com/art/organum organum]". ''Encyclopedia Britannica''. November 12, 2010. Accessed February 21, 2026.</ref>

In organum's simplest form, the plainchant was doubled in a perfect interval like the fourth, fifth, or octave.<ref>Duarte, John. ''Melody & Harmony for Guitarists''. Mel Bay Publications, Incorporated, 2010. 49.</ref> Chords were incidental results of the melodic lines.<ref name=Benward>Benward, Bruce, and Saker, Marilyn. ''[https://archive.org/details/musicintheorypra0000benw_s4e5/mode/1up Music in Theory and Practice, Volume 1]''. McGraw-Hill Education, 2008.</ref>{{rp|77, 220}}

During the Renaissance, polyphony became more complex. Seventh chords started to appear in the 16th century.<ref name=Benward/>{{rp|237}} In the Baroque era, seventh chords started to function in specific ways that enabled smooth voice leading and complex cadences. The dominant seventh chord in particular became a fixture of classical music during the common practice period.<ref name=Benward/>{{rp|237f}}

For Baroque composers, counterpoint was no longer imperative, and melodies were often accompanied simply by chords.<ref name=Benward/>{{rp|77}} The era also saw the rise of a shorthand notation known as figured or thorough bass. The bass melody is accompanied by numbers which indicate the harmony that should be played above each note.<ref>Schonberg, Harold C. ''[https://archive.org/details/livesofgreatcomp0000scho/page/25/mode/1up The Lives of the Great Composers]''. United Kingdom, WW Norton, 1970. 25.</ref><ref>Dunstan, Ralph. ''[https://www.google.com/books/edition/Basses_and_Melodies_for_Students_of_Harm/huosAAAAYAAJ?hl=en&gbpv=1&pg=PA1 Basses and Melodies for Students of Harmony and Players from Figured Basses: Selected from the Works of the Great Composers]''. London: Novello, Ewer, and Comapny, 1894. 1.</ref>

As tonality expanded, structures like Neapolitan and augmented sixth chords used chromatic notes outside of the diatonic scale.<ref>Drabkin, William. "[https://www.oxfordmusiconline.com/grovemusic/view/10.1093/gmo/9781561592630.001.0001/omo-9781561592630-e-0000019658 Neapolitan sixth chord]." ''Grove Music Online''. Oxford University Press, 2001.</ref> Such altered chords complicated voice leading and led to more eclectic cadences and modulations. Composers began to strip the function from such chords and embrace them purely for their sonic qualities.<ref name=Harvard>DeVoto, Mark. "[https://archive.org/details/newharvarddictio00rand/page/363/mode/1up Harmonic Analysis]", ''The New Harvard Dictionary of Music''. Edited by Don Randel. Belknap Press of Harvard University Press, 1986. 362f.</ref><ref>"[https://archive.org/details/newharvarddictio00rand/page/122/mode/1up Cadence]", ''The New Harvard Dictionary of Music'', 1986. 122f.</ref> 20th century music greatly expanded chords, adding tones and often dissonance. Jazz has a particularly eclectic chord vocabulary.<ref>Pachet, François. "[https://hal.science/hal-03112196 Surprising Harmonies", ''Journées d'Informatique Musicale'']. May 1999, Paris, France. 187–206.</ref>

==Structure== [[File:Thirteenth-polychord.PNG|thumb|The C major thirteenth chord can be seen as a polychord combination of several different chords.]]Just as scales derive from the harmonic series, the major chord is likewise formed by overtones 4, 5, and 6. The next overtone creates a seventh chord.<ref name=Schoenberg83>Schoenberg, Arnold. ''[https://archive.org/details/theoryofharmony0000scho/mode/1up Theory of Harmony]''. Translated by Roy E. Carter. University of California Press, 1983.</ref>{{rp|26}} A common triad has three notes: the root, third, and fifth. The intervals are identified by their distance from the root of the chord.<ref name=GroveC/> The notes that form a chord are sometimes called members or factors.<ref>Neidhöfer, Christoph, and Peter Schubert. "[https://doi.org/10.2307/jj.18254082.5 MELODY OR HARMONY?]" ''Baroque Counterpoint: Revised and Expanded Edition''. State University of New York Press, 2023. 14.</ref><ref name=Solomon>Solomon, Jason W. ''Music Theory Essentials: A Streamlined Approach to Fundamentals, Tonal Harmony, and Post-Tonal Materials''. United Kingdom, Taylor & Francis, 2019.</ref>{{rp|78}}

Continuing up in thirds yields a seventh, ninth, eleventh, and thirteenth before returning to the root again. Complex sonorities larger than a tetrad are sometimes called polychords because they can be seen as combinations of two different chords.<ref>Haerle, Dan. ''The Jazz Language: A Theory Text for Jazz Composition and Improvisation''. Columbia Pictures Publications, 1980. 30.</ref><ref name=Solomon/>{{rp|241f}} Extended chords are one of the central characteristics of jazz harmony.<ref>Sadie, Stanley, ed. "[https://archive.org/details/newgrovedictiona0013unse_j7s4/page/252/mode/1up Ninth chord]". ''The New Grove Dictionary of Music and Musicians''. vol. 13. MacMillan Publishers, 1980. 252.</ref>

Chords are identified by their intervals.<ref name=GroveC/> The four basic triad qualities are major, minor, diminished, and augmented. Major and minor chords derive from the quality of their thirds. Diminished and augmented chords describe the quality of the fifth.<ref>Hutchinson, Robert. "[https://musictheory.pugetsound.edu/mt21c/TriadsIntroduction.html Introduction to Triads]". ''[https://musictheory.pugetsound.edu/mt21c/frontmatter.html Music Theory for the 21st-Century Classroom]''. University of Puget Sound, 2025.</ref> Additional intervals like sevenths are also described by their quality in relation to the root.<ref name=Benward/>{{rp|235}}

Composers began expanding tonality beyond the common practice and often structured chords in fourths and fifths. They were more tonally ambiguous, enabling new patterns for music.<ref name="Schoenberg">Arnold Schoenberg, ''Structural Functions of Harmony'', Faber and Faber, 1983, pp. 1–2.</ref>{{rp|399–407}} Chords also shrunk to tone clusters made of small intervals like seconds. The resulting sound mass was a common feature in the 20th century.<ref>Cope, David. ''[https://archive.org/details/unset0000unse_x4d7/page/55/mode/1up New Directions in Music]''. Waveland Press, 2001. 55–66.</ref> Microtonal chords are also used by many contemporary composers.<ref>Lerdahl, Fred. ''Composition and Cognition: Reflections on Contemporary Music and the Musical Mind''. University of California Press, 2019. 102.</ref><ref>''The Oxford Handbook of Spectral Music''. Oxford University Press, 2025. 853.</ref><ref>Gilmore, Bob. ''Harry Partch: A Biography''. Yale University Press, 1998. 207.</ref>

{{Image frame|content=<score> { \override Score.TimeSignature #'stencil = ##f \override Score.SpacingSpanner.strict-note-spacing = ##t \set Score.proportionalNotationDuration = #(ly:make-moment 1/4) \time 4/4 \relative c' { <c e g bes>1^\markup { \column { Root } } <e g bes c>1^\markup { \column { 1st} } <g bes c e>1^\markup { \column { 2nd } } <bes c e g>1^\markup { \column { 3rd } } } } </score>|width= 400|caption = A seventh chord in root position, first, second, and third inversion.<ref name=Inversion/>}} Theorists began to analyze the structure of chords in the 16th century. Jean-Philippe Rameau developed the nomenclature for chord inversion that is still in use today.<ref>Mitchell, William J. "[https://doi.org/10.2307/829943 Chord and Context in 18th-Century Theory]." ''Journal of the American Musicological Society'', vol. 16, no. 2, 1963. 222–5.</ref>

Root position is when the lowest note of a chord is the root, regardless of how the other members are arranged above it. The chord is considered inverted when the root is not the lowest voice. When the third is the lowest sounding pitch, the chord is in first inversion. The second inversion puts the fifth in the bass and was widely seen as dissonant, even as composers put it into frequent practice.<ref name=Inversion>"[https://archive.org/details/newharvarddictio00rand/page/403/mode/1up Inversion]", ''The New Harvard Dictionary of Music'', 1986. 403f.</ref><ref>Bartlette, Christopher, and Steven Laitz, Steven. ''Graduate Review of Tonal Theory''. Oxford University Press, 2010. 58.</ref>

==Function== {| class="wikitable floatright" |+Roman Numerals and Scale Degrees for Major Keys<ref>Rollinson, Thomas H.''[https://www.google.com/books/edition/Treatise_on_Harmony_Counterpoint_Instrum/xOEsAAAAYAAJ?hl=en&gbpv=1&pg=PA10&printsec=frontcover Treatise on Harmony, Counterpoint, Instrumentation and Orchestration]'' Philadelphia: J.W. Pepper & Son, 1886. 12.</ref> |- ! Roman<br>Numeral ! Scale Degree |- | style="text-align: center;" | I || tonic |- | style="text-align: center;" | ii || supertonic |- | style="text-align: center;" | iii || mediant |- | style="text-align: center;" | IV || subdominant |- | style="text-align: center;" | V || dominant |- | style="text-align: center;" | vi || submediant |- | style="text-align: center;" | VII || subtonic |- | style="text-align: center;"|vii||leading tone |}The names for each scale degree were bestowed on the triads above them. The dominant fifth scale degree is the root of the dominant fifth chord.<ref name=Solomon/>{{rp|41}} Chords retained similar relationships to the tonic as their scalar forbearers. The dominant functioned as a counterweight to the tonic. A simple progression away from the tonic to the dominant and back again is the template for countless short pieces.<ref name=Piston>Piston, Walter. ''[https://archive.org/details/harmony0000pist_h2q1/page/49/mode/1up Harmony]'' New York: W.W. Norton & Company, 1978.</ref>{{rp|49}}

Hugo Riemann built on Rameau's work to develop an idea of functional harmony where every chord was analyzed by its relationship to the tonic or dominant.<ref>Mickelsen, William C. ''[https://archive.org/details/hugoriemannstheo0000mick/page/61/mode/1up Hugo Riemann's Theory of Harmony: A Study]''. University of Nebraska Press, 1977.</ref> His work was widely adapted by other theorists.<ref>Holtmeier, Ludwig. "The Reception of Hugo Riemann's Music Theory", ''The Oxford Handbook of Neo-Riemannian Music Theories''. Oxford University Press, 2011. 6.</ref>

Chords inherited their behavior from the part writing traditions of polyphony. The inner voices of chords reflected the same relationships as their melodic counterparts. The dissonance of the tritone in a dominant seventh chord is resolved stepwise in traditional part writing, with the seventh stepping down to the third and the leading tone stepping up to the tonic.<ref>Benjamin, Thomas, et al. ''Techniques and Materials of Music from the Common Practice Period Through the Twentieth Century''. Australia, Cengage, 2015. 46–49.</ref>

As music became more chromatic, composers broadened the vocabulary of chords. Chords were often borrowed from other keys without modulation.<ref>Prout, Ebenezer. ''[https://www.google.com/books/edition/Harmony/AWEyAAAAMAAJ?hl=en&gbpv=1&pg=PA199&printsec=frontcover Harmony: Its Theory and Practice]''. United Kingdom, Augener & Company, 1903. 198f.</ref> Altered chords obscured the root relationships in music to the point where tonality could be asserted simply by a composer's emphasis.<ref>Erickson, Robert. ''[https://archive.org/details/structureofmusic0000eric_q4l4/page/85/mode/1up The Structure of Music: A Listener's Guide]''. New York: Noonday Press, 1977. 85–88.</ref>

Chords can be spelled and analyzed in a dizzying number of ways. What remains most essential is how they sound.<ref>Hanson, Howard. ''[https://archive.org/details/harmonicmaterial00hans/mode/2up Harmonic Materials of Modern Music]''. New York: Appleton-Century-Crofts, 1960. 2.</ref> In the 18th century, Roman numerals were used to label chords, and the practice is still in use.<ref name=GroveH/> In the 20th century, this approach evolved into a shorthand known as the Nashville Number System.<ref>Costello, Patrick. ''[https://archive.org/details/howtaooffolkguit0001patr/page/54/mode/1up The how and the Tao of Folk Guitar: Volume One: Getting Started]''. United States, Pick-Ware Publishing, 2003. 54.</ref> Music theorists also simply label chords by the letter of their roots, accompanied by symbols to indicate quality and added tones. This practice is also common in popular music.<ref name=Benward/>{{rp|74f}}

==References== {{reflist}}

==Further reading== *Andrews, William G; Sclater, Molly (2000). ''Materials of Western Music Part 1''. Alfred Publishing Company, Incorporated. *Bartlette, Christopher; Laitz, Steven G. (2010). ''Graduate Review of Tonal Theory''. New York: Oxford University Press. *Benjamin, T.; Horvit, M.; Nelson, R.; Koozin, T. (2014). ''Techniques and Materials of Music: From the Common Practice Period Through the Twentieth Century'' (Enhanced ed.). Cengage Learning. * Dahlhaus, Carl. Gjerdingen, Robert O. trans. (1990). ''Studies in the Origin of Harmonic Tonality'', p. 67. Princeton University Press. {{ISBN|0-691-09135-8}}. *Dalla Riva, Chris. ''Uncharted Territory: What Numbers Tell Us about the Biggest Hit Songs and Ourselves''. Bloomsbury Publishing, 2025. * Grout, Donald Jay (1960). ''A History Of Western Music''. Norton Publishing. *Mayfield, Connie E. (2012). ''Theory Essentials''. Cengage Learning. *Miller, Michael (2005). ''The Complete Idiot's Guide to Music Theory''. Penguin. *Persichetti, Vincent (1961). ''[https://archive.org/details/isbn_9780393095395 Twentieth-century Harmony: Creative Aspects and Practice]''. New York: W. W. Norton. *Policastro, Michael A. (1999). ''Understanding How to Build Guitar Chords and Arpeggios''. Mel Bay Publications. *Tanguiane, Andranick (1993). ''Artificial Perception and Music Recognition''. Lecture Notes in Artificial Intelligence. Vol. 746. Berlin-Heidelberg: Springer. *Tanguiane, Andranick (1994). "[https://www.jstor.org/stable/40285634 A principle of correlativity of perception and its application to music recognition]". ''Music Perception''. 11 (4): 465–502.

==External links== * {{Wikiquote-inline}} * {{Commons category-inline|Chords}}

{{DEFAULTSORT:Chord (Music)}} * Category:Harmony Category:Accompaniment Category:Music theory