Cello in the context of Pipe organ

A musical ensemble, also known as a music group, musical group, or a band is a group of people who perform instrumental and/or vocal music, with the ensemble typically known by a distinct name. Some music ensembles consist solely of instrumentalists, such as the jazz quartet or the orchestra. Other music ensembles consist solely of singers, such as choirs and doo-wop groups. In both popular music and classical music, there are ensembles in which both instrumentalists and singers perform, such as the rock band or the Baroque chamber group for basso continuo (harpsichord and cello) and one or more singers. In classical music, trios or quartets either blend the sounds of musical instrument families (such as piano, strings, and wind instruments) or group instruments from the same instrument family, such as string ensembles (e.g., string quartet) or wind ensembles (e.g., wind quintet). Some ensembles blend the sounds of a variety of instrument families, such as the orchestra, which uses a string section, brass instruments, woodwinds, and percussion instruments, or the concert band, which uses brass, woodwinds, and percussion. In jazz ensembles or combos, the instruments typically include wind instruments (one or more saxophones, trumpets, etc.), one or two chordal "comping" instruments (electric guitar, acoustic guitar, piano, or Hammond organ), a bass instrument (bass guitar or double bass), and a drummer or percussionist. Jazz ensembles may be solely instrumental, or they may consist of a group of instruments accompanying one or more singers. In rock and pop ensembles, usually called rock bands or pop bands, there are usually guitars and keyboards (piano, electric piano, Hammond organ, synthesizer, etc.), one or more singers, and a rhythm section made up of a bass guitar and drum kit.

Music ensembles typically have a leader. In jazz bands, rock and pop groups, and similar ensembles, this is the band leader. In classical music, orchestras, concert bands, and choirs are led by a conductor. In orchestra, the concertmaster (principal first violin player) is the instrumentalist leader of the orchestra. In orchestras, the individual sections also have leaders, typically called the "principal" of the section (e.g., the leader of the viola section is called the "principal viola"). Conductors are also used in jazz big bands and in some very large rock or pop ensembles (e.g., a rock concert that includes a string section, a horn section, and a choir that accompanies a rock band's performance).

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.

Bassline (also known as a bass line or bass part) is the term used in many styles of music, such as blues, jazz, funk, dub and electronic, traditional, and classical music, for the low-pitched instrumental part or line played (in jazz and some forms of popular music) by a rhythm section instrument such as the electric bass, double bass, cello, tuba or keyboard (piano, Hammond organ, electric organ, or synthesizer).

In unaccompanied solo performance, basslines may simply be played in the lower register of any instrument while melody and/or further accompaniment is provided in the middle or upper register. In solo music for piano and pipe organ, these instruments have an excellent lower register that can be used to play a deep bassline. On organs, the bass line is typically played using the pedal keyboard and massive 16' and 32' bass pipes.

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 six Cello Suites, BWV 1007–1012, are suites for unaccompanied cello by Johann Sebastian Bach (1685–1750). They are some of the most frequently performed solo compositions ever written for cello. Bach most likely composed them during the period 1717–1723, when he served as Kapellmeister in Köthen. The title given on the cover of the Anna Magdalena Bach manuscript was Suites à Violoncello Solo senza Basso (Suites for cello solo without bass).

As usual in a Baroque musical suite, after the prelude which begins each suite, all the other movements are based around baroque dance types. The cello suites are structured in six movements each: prelude, allemande, courante, sarabande, two minuets or two bourrées or two gavottes, and a final gigue. Gary S. Dalkin of MusicWeb International called Bach's cello suites "among the most profound of all classical music works" and Wilfrid Mellers described them in 1980 as "Monophonic music wherein a man has created a dance of God".

The violin family of musical instruments was developed in Italy in the 16th century. At the time the name of this family of instruments was viole da braccio which was used to distinguish them from the viol family (viole da gamba). The standard modern violin family consists of the violin, viola, cello, and (possibly) double bass.

Instrument names in the violin family are all derived from the root viola, which is a derivative of the Medieval Latin word vitula (meaning "stringed instrument"). A violin is a "little viola", a violone is a "big viola" or a bass violin, and a violoncello (often abbreviated cello) is a "small violone" (or literally, a "small big viola"). (The violone is not part of the modern violin family; its place is taken by the modern double bass, an instrument with a mix of violin and viol characteristics.)

In music, a bow (/boʊ/) is a tensioned stick which has hair (usually horse-tail hair) coated in rosin (to facilitate friction) affixed to it. It is moved across some part (generally some type of strings) of a musical instrument to cause vibration, which the instrument emits as sound. The vast majority of bows are used with string instruments, such as the violin, viola, cello, and bass, although some bows are used with musical saws and other bowed idiophones.

A vibration in a string is a wave. Initial disturbance (such as plucking or striking) causes a vibrating string to produce a sound with constant frequency, i.e., constant pitch. The nature of this frequency selection process occurs for a stretched string with a finite length, which means that only particular frequencies can survive on this string. If the length, tension, and linear density (e.g., the thickness or material choices) of the string are correctly specified, the sound produced is a musical tone. Vibrating strings are the basis of string instruments such as guitars, cellos, and pianos. For a homogeneous string, the motion is given by the wave equation.

The theorbo is a plucked string instrument of the lute family, with an extended neck that houses the second pegbox. Like a lute, a theorbo has a curved-back sound box with a flat top, typically with one or three sound holes decorated with rosettes. As with the lute, the player plucks or strums the strings with the right hand while "fretting" (pressing down) the strings with the left hand.

The theorbo is related to the liuto attiorbato, the French théorbe des pièces, the archlute, the German baroque lute, and the angélique (or angelica). A theorbo differs from a regular lute in its re-entrant tuning in which the first two strings are tuned an octave lower. The theorbo was used during the Baroque music era (1600–1750) to play basso continuo accompaniment parts (as part of the basso continuo group, which often included harpsichord, pipe organ and bass instruments), and also as a solo instrument. It has a range similar to that of cello.

A bridge is a device that supports the strings on a stringed musical instrument and transmits the vibration of those strings to another structural component of the instrument—typically a soundboard, such as the top of a guitar or violin—which transfers the sound to the surrounding air. Depending on the instrument, the bridge may be made of carved wood (violin family instruments, acoustic guitars and some jazz guitars), metal (electric guitars such as the Fender Telecaster) or other materials. The bridge supports the strings and holds them over the body of the instrument under tension.

Catgut (also known as gut) is a type of cord that is prepared from the natural fiber found in the walls of animal intestines.Catgut makers usually use sheep or goat intestines, but occasionally use the intestines of cattle,hogs, horses, mules, or donkeys. Despite the name, catgut has never been made from cat intestines.

A symphony is an extended musical composition in Western classical music, most often for orchestra. Although the term has had many meanings from its origins in the ancient Greek era, by the late 18th century the word had taken on the meaning common today: a work usually consisting of multiple distinct sections or movements, often four, with the first movement in sonata form. Symphonies are almost always scored for an orchestra consisting of a string section (violin, viola, cello, and double bass), brass, woodwind, and percussion instruments which altogether number about 30 to 100 musicians. Symphonies are notated in a musical score, which contains all the instrument parts. Orchestral musicians play from parts which contain just the notated music for their own instrument. Some symphonies also contain vocal parts (e.g., Beethoven's Ninth Symphony, or Mahler's Second Symphony).

The term string quartet is a type of musical composition or a group of four people who play them. Many composers from the mid-18th century onwards wrote string quartets. The associated musical ensemble consists of two violinists, a violist, and a cellist.

The string quartet was developed into its present form by the Austrian composer Joseph Haydn, whose works in the 1750s established the ensemble as a group of four more-or-less equal partners. Since that time, the string quartet has been considered a prestigious form; writing for four instruments with broadly similar characteristics both constrains and tests a composer. String quartet composition flourished in the Classical era, and Mozart, Beethoven and Schubert each wrote a number of them. Many Romantic and early-twentieth-century composers composed string quartets, including Mendelssohn, Schumann, Brahms, Dvořák, Janáček, and Debussy. There was a slight lull in string quartet composition later in the 19th century, but it received a resurgence in the 20th century, with the Second Viennese School, Bartók, Shostakovich, Babbitt, and Carter producing highly regarded examples of the genre, and it remains an important and refined musical form.

The string section of an orchestra is composed of bowed instruments belonging to the violin family. It normally consists of first and second violins, violas, cellos, and double basses. It is the most numerous group in the standard orchestra. In discussions of the instrumentation of a musical work, the phrase "the strings" or "and strings" is used to indicate a string section as just defined. An orchestra consisting solely of a string section is called a string orchestra. Smaller string sections are sometimes used in jazz, pop, and rock music and in the pit orchestras of musical theatre.

The viola (/viˈoʊlə/ vee-OH-lə, () Italian: [ˈvjɔːla, viˈɔːla]) is a string instrument of the violin family, and is usually bowed when played. Violas are slightly larger than violins, and have a lower sound. Since the 18th century, it has been the middle or alto voice of the violin family, between the violin (which is tuned a perfect fifth higher) and the cello (which is tuned an octave lower). The strings from low to high are typically tuned to C₃, G₃, D₄, and A₄.

In the past, the viola varied in size and style, as did its names. The word viola originates from the Italian language. The Italians often used the term viola da braccio, meaning, literally, 'of the arm'. "Brazzo" was another Italian word for the viola, which the Germans adopted as Bratsche. The French had their own names: cinquiesme was a small viola, haute contre was a large viola, and taile was a tenor. Today, the French use the term alto, a reference to its range.