Pipe organ in the context of Volume pedal

An orchestra (/ˈɔːrkɪstrə/ ; OR-ki-strə) is a large instrumental ensemble typical of classical music, which combines instruments from different families. There are typically four main sections of instruments:

• The string section, including the violin, viola, cello, and double bass
• The woodwind section, including the flute, oboe, clarinet, bassoon, and occasionally saxophone
• The brass section, including the French horn (commonly known as the "horn"), trumpet, trombone, cornet, and tuba, and sometimes euphonium
• The percussion section, including the timpani, snare drum, bass drum, cymbals, triangle, tambourine, tam-tam and mallet percussion instruments

Other instruments such as the piano, harpsichord, pipe organ, and celesta may sometimes appear in a fifth keyboard section or may stand alone as soloist instruments, as may the concert harp and, for performances of some modern compositions, electronic instruments, and guitars.

Accompaniment is the musical part which provides the rhythmic and/or harmonic support for the melody or main themes of a song or instrumental piece. There are many different styles and types of accompaniment in different genres and styles of music. In homophonic music, the main accompaniment approach used in popular music, a clear vocal melody is supported by subordinate chords. In popular music and traditional music, the accompaniment parts typically provide the "beat" for the music and outline the chord progression of the song or instrumental piece.

The accompaniment for a vocal melody or instrumental solo can be played by a single musician playing an instrument such as piano, pipe organ, or guitar. While any instrument can in theory be used as an accompaniment instrument, keyboard and guitar-family instruments tend to be used if there is only a single instrument, as these instruments can play chords and basslines simultaneously (chords and a bassline are easier to play simultaneously on keyboard instruments, but a fingerpicking guitarist can play chords and a bassline simultaneously on guitar). A solo singer can accompany themself by playing guitar or piano while they sing, and in some rare cases, a solo singer can even accompany themself just using their voice and body (e.g., Bobby McFerrin).

Johann Sebastian Bach (31 March [O.S. 21 March] 1685 – 28 July 1750) was a German composer and musician of the late Baroque period. He is known for his prolific output across a variety of instruments and forms, including the orchestral Brandenburg Concertos; solo instrumental works such as the cello suites and sonatas and partitas for solo violin; keyboard works such as the Goldberg Variations and The Well-Tempered Clavier; organ works such as the Schübler Chorales and the Toccata and Fugue in D minor; and choral works such as the St Matthew Passion and the Mass in B minor. Since the 19th-century Bach Revival, he has been widely regarded as one of the greatest composers in the history of Western music.

The Bach family had already produced several composers when Johann Sebastian was born as the last child of a city musician, Johann Ambrosius, in Eisenach. After being orphaned at age 10, he lived for five years with his eldest brother, Johann Christoph, then continued his musical education in Lüneburg. In 1703 he returned to Thuringia, working as a musician for Protestant churches in Arnstadt and Mühlhausen. Around that time he also visited for longer periods the courts in Weimar, where he expanded his organ repertory, and the reformed court at Köthen, where he was mostly engaged with chamber music. By 1723 he was hired as Thomaskantor (cantor with related duties at St Thomas School) in Leipzig. There he composed music for the principal Lutheran churches of the city and Leipzig University's student ensemble, Collegium Musicum. In 1726 he began publishing his organ and other keyboard music. In Leipzig, as had happened during some of his earlier positions, he had difficult relations with his employer. This situation was somewhat remedied when his sovereign, Augustus III of Poland, granted him the title of court composer of the Elector of Saxony in 1736. In the last decades of his life, Bach reworked and extended many of his earlier compositions. He died due to complications following eye surgery in 1750 at the age of 65. Four of his twenty children, Wilhelm Friedemann, Carl Philipp Emanuel, Johann Christoph Friedrich, and Johann Christian, became composers.

An organ pipe is a sound-producing element of the pipe organ that resonates at a specific pitch when pressurized air (commonly referred to as wind) is driven through it. Each pipe is tuned to a note of the musical scale. A set of organ pipes of similar timbre comprising the complete scale is known as a rank; one or more ranks constitutes a stop.

In music, the organ is a keyboard instrument of one or more pipe divisions or other means (generally woodwind or electric) for producing tones. The organs have usually two or three, sometimes up to five or more, manuals for playing with the hands and a pedalboard for playing with the feet. With the use of registers, several groups of pipes can be connected to one manual.

The organ has been used in various musical settings, particularly in classical music. Music written specifically for the organ is common from the Renaissance to the present day. Pipe organs, the most traditional type, operate by forcing air through pipes of varying sizes and materials, each producing a different pitch and tone. These instruments are commonly found in churches and concert halls, where they have long been associated with liturgical music and grand ceremonial occasions.

A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, shorter keys that repeats at the interval of an octave. Pressing a key on the keyboard makes the instrument produce sounds—either by mechanically striking a string or tine (acoustic and electric piano, clavichord), plucking a string (harpsichord), causing air to flow through a pipe organ, striking a bell (carillon), or activating an electronic circuit (synthesizer, digital piano, electronic keyboard). Since the most commonly encountered keyboard instrument is the piano, the keyboard layout is often referred to as the piano keyboard or simply piano keys.

Notre-Dame de Paris (French: Cathédrale Notre-Dame de Paris French: [nɔtʁ(ə) dam də paʁi] : "Cathedral of Our Lady of Paris"), often referred to simply as Notre-Dame, is a medieval Catholic cathedral on the Île de la Cité (an island in the River Seine), in the 4th arrondissement of Paris, France. It is the cathedral church of the Roman Catholic Archdiocese of Paris.

The cathedral, dedicated to the Virgin Mary ("Our Lady"), is considered one of the finest examples of French Gothic architecture. Several attributes set it apart from the earlier Romanesque style, including its pioneering use of the rib vault and flying buttress, its enormous and colourful rose windows, and the naturalism and abundance of its sculptural decoration. Notre-Dame is also exceptional for its three pipe organs (one historic) and its immense church bells.

On 15 April 2019, at 18:18 CEST, a structural fire broke out in the roof space of Notre-Dame de Paris, a medieval Catholic cathedral in Paris, France, that is part of the "Paris, Banks of the Seine" UNESCO World Heritage Site.

The fire, which investigators believe was started by a cigarette or an electrical short circuit, destroyed the cathedral's wooden spire (flèche) and most of the wooden roof and severely damaged the cathedral's upper walls. The vaulted stone ceiling largely contained the burning roof as it collapsed, preventing extensive damage to the interior. Many works of art and religious relics were moved to safety, but others suffered smoke damage, and some of the exterior art was damaged or destroyed. The cathedral's altar, two pipe organs, and three 13th-century rose windows suffered little or no damage. Three emergency workers were injured. The fire contaminated the site and nearby areas of Paris with toxic dust and lead.

A choir (/ˈkwaɪər/ KWIRE), also known as a chorale or chorus (from Latin chorus, meaning 'a dance in a circle'), is a musical ensemble of singers. Choral music, in turn, is the music written specifically for such an ensemble to perform or in other words is the music performed by the ensemble. Choirs may perform music from the classical music repertoire, which spans from the medieval era to the present, or popular music repertoire. Most choirs are led by a conductor, who leads the performances with arm, hand, and facial gestures.

The term choir is very often applied to groups affiliated with a church (whether or not they actually occupy the quire), whereas a chorus performs in theatres or concert halls, but this distinction is not rigid. Choirs may sing without instruments, or accompanied by a piano, accordion, pipe organ, a small ensemble, or an orchestra.

A chorale is the name of several related musical forms originating in the music genre of the Lutheran chorale:

• Hymn tune of a Lutheran hymn (e.g. the melody of "Wachet auf, ruft uns die Stimme"), or a tune in a similar format (e.g. one of the themes in the Finale of Saint-Saëns's Third Symphony)
• Such tune with a harmonic accompaniment (e.g. chorale monody, chorales included in Schemellis Gesangbuch)
• Such a tune presented in a homophonic or homorhythmic harmonisation, usually four-part harmony (e.g. Bach's four-part chorales, or the chorale included in the second movement of Mahler's Fifth Symphony)
• A more complex setting of a hymn-like tune (e.g. chorale fantasia form in Bach's Schübler Chorales, or a combination of compositional techniques in César Franck's Three Chorales [fr])

The chorale originated when Martin Luther translated sacred songs into the vernacular language (German), contrary to the established practice of church music near the end of the first quarter of the 16th century. The first hymnals according to Luther's new method were published in 1524. Luther and his followers not only wrote metrical hymn lyrics, but also composed metrical musical settings for these texts. This music was partially based on established melodies of church hymns and known secular songs. In the 17th century the repertoire was enriched with more choral and organ settings of the chorale tunes. By the end of the century a four-part setting for SATB voices had become the standard for the choral settings, while the congregational singing of chorales was tending towards monody with an instrumental accompaniment. The prolific creation of new Lutheran chorale tunes ended around that time.

The violoncello (/ˌvaɪələnˈtʃɛloʊ/ VY-ə-lən-CHEL-oh, Italian pronunciation: [vjolonˈtʃɛllo]), commonly abbreviated as cello (/ˈtʃɛloʊ/ CHEL-oh), is a medium-low pitched bowed (sometimes plucked and occasionally hit) string instrument of the violin family. Its four strings are usually tuned in perfect fifths: from low to high, C₂, G₂, D₃ and A₃. The viola's four strings are each an octave higher. Music for the cello is generally written in the bass clef; the tenor clef and treble clef are used for higher-range passages.

Played by a cellist or violoncellist, it enjoys a large solo repertoire with and without accompaniment, as well as numerous concerti. As a solo instrument, the cello uses its whole range, from bass to soprano, and in chamber music, such as string quartets and the orchestra's string section, it often plays the bass part, where it may be reinforced an octave lower by the double basses. Figured bass music of the Baroque era typically assumes a cello, viola da gamba or bassoon as part of the basso continuo group alongside chordal instruments such as organ, harpsichord, lute, or theorbo. Cellos are found in many other ensembles, from modern Chinese orchestras to cello rock bands.

The Hammond organ is an electric organ invented by Laurens Hammond and John M. Hanert, first manufactured in 1935. Multiple models have been produced, most of which use sliding drawbars to vary sounds. Until 1975, sound was created from rotating a metal tonewheel near an electromagnetic pickup, and amplifying the electric signal into a speaker cabinet. The organ is commonly used with the Leslie speaker.

Around two million Hammond organs have been manufactured. The organ was originally marketed by the Hammond Organ Company to churches as a lower-cost alternative to the wind-driven pipe organ, or instead of a piano. It quickly became popular with professional jazz musicians in organ trios—small groups centered on the Hammond organ. Jazz club owners found that organ trios were cheaper than hiring a big band. Jimmy Smith's use of the Hammond B-3, with its additional harmonic percussion feature, inspired a generation of organ players, and its use became more widespread in the 1960s and 1970s in genres such as rhythm and blues, rock (especially progressive rock), and reggae.

The keyboard section of an orchestra or concert band includes keyboard instruments. Keyboard instruments are not usually a standard members of a modern orchestra or concert band, but they are included occasionally. In orchestras from the 1600s to the mid-1750s, a keyboard instrument such as the pipe organ or harpsichord was normally played with an orchestra, with the performer improvising chords from a figured bass part. This practice, called basso continuo, was phased out after 1750 (although some Masses for choir and orchestra would occasionally still have a keyboard part in the late 1700s).

A pedalboard (also called a pedal keyboard, pedal clavier, or, with electronic instruments, a bass pedalboard) is a keyboard played with the feet that is usually used to produce the low-pitched bass line of a piece of music. A pedalboard has long, narrow lever-style keys laid out in the same semitone scalar pattern as a manual keyboard, with longer keys for C, D, E, F, G, A, and B, and shorter, raised keys for C♯, D♯, F♯, G♯ and A♯. Training in pedal technique is part of standard organ pedagogy in church music and art music.

Pedalboards are found at the base of the console of most pipe organs, pedal pianos, theatre organs, and electronic organs. Standalone pedalboards such as the 1970s-era Moog Taurus bass pedals are occasionally used in progressive rock and fusion music. In the 21st century, MIDI pedalboard controllers are used with synthesizers, electronic Hammond-style organs, and with digital pipe organs. Pedalboards are also used with pedal pianos and with some harpsichords, clavichords, and carillons (church bells).