A piano is a keyboard instrument that makes sound when its keys are pressed. Pressing a key activates a mechanism that causes hammers to strike strings inside the piano. Most modern pianos have 88 black and white keys, except for some special models like Bosendörfer and Stuart & Sons pianos. These keys are tuned to all the notes in the musical scale using equal temperament. A person who plays the piano is called a pianist.

There are two main types of piano: the grand piano and the upright piano. The grand piano produces better sound and allows for more precise control of the keys, making it the preferred choice when space and money are available. It is also often used in places where skilled pianists perform. The upright piano is more common because it is smaller and less expensive.

When a key is pressed, hammers made of wood covered in felt strike the strings inside the piano. The vibrations from the strings travel through a bridge to a soundboard, which makes the sound louder by sending the sound into the air. When the key is released, a damper stops the string from vibrating, ending the sound. Most notes have three strings, except for the lowest notes, which have one or two strings. Pianists can hold notes longer by using pedals at the bottom of the piano. These pedals lift the dampers, allowing the strings to continue vibrating. The sustain pedal lets pianists layer sounds together, creating a more expressive and colorful musical effect.

In the 19th century, changes to the piano were influenced by Romantic music. These changes included using a cast iron frame, which allowed the strings to be tightened more. A technique called aliquot stringing gave grand pianos a stronger, longer-lasting sound with a richer tone. Later in the century, as pianos became more common, families could enjoy new music by having a family member play simpler versions of the pieces.

The piano is used in many types of music, including classical, jazz, traditional, and popular music. It is used for solo performances, group music, accompaniment, and for writing and practicing music. Even though pianos are heavy and expensive, their usefulness, the training of musicians, and their presence in schools, concert halls, and practice rooms have made them a common instrument in Western countries.

History

The piano was developed from earlier inventions in struck-string and keyboard instruments. The first known keyboard instrument was the Ancient Greek hydraulis, a type of pipe organ created in the third century BC. Pipe organs were used in Europe during the Middle Ages, helping builders learn how to make keyboard mechanisms that could produce different pitches. The first string instruments with struck strings were hammered dulcimers, which came from the Middle East and were brought to Europe during the Middle Ages. In the Middle Ages, several attempts were made to create stringed keyboard instruments with struck strings. By the 17th century, keyboard instruments like the clavichord and harpsichord had well-developed mechanisms. In a clavichord, strings are struck by tangents, while in a harpsichord, they are plucked by quills when a key is pressed. Years of work on the harpsichord helped builders learn how to make cases, soundboards, bridges, and mechanical actions for keyboards that could sound strings.

The word "piano" comes from the Italian "pianoforte," which means "harpsichord with soft and loud." Changes in volume depend on how hard a pianist presses the keys: the harder the pressure, the louder the sound and the stronger the attack. The fortepiano, invented in 1700, was the second keyboard instrument (after the clavichord) to allow changes in volume and tone based on how forcefully or softly the keys were pressed, unlike the pipe organ and harpsichord.

The invention of the piano is credited to Bartolomeo Cristofori of Padua, Italy. He worked for Ferdinando de' Medici, Grand Prince of Tuscany, as the Keeper of the Instruments. Cristofori was an expert in making harpsichords and understood the knowledge about stringed keyboard instruments. This knowledge helped him create the first pianos. An inventory from the Medici family shows a piano existed by 1700. Three surviving Cristofori pianos date from the 1720s. Cristofori named the instrument "un cimbalo di cipresso di piano e forte," which later became "pianoforte," "fortepiano," and eventually "piano."

Cristofori's success was designing a keyboard instrument where hammers strike the strings. The hammer must hit the string but not stay in contact, or the sound would stop. After striking, the hammer must quickly return to its resting position without bouncing, so it is ready to play again. His piano action influenced many later designs.

Cristofori's early pianos had thin strings and were quieter than modern pianos but louder and had more sustain than the clavichord, which was the only previous keyboard instrument that could change volume based on touch. The harpsichord could produce loud sounds but had no control over individual note dynamics. The piano combined the loudness of the harpsichord with the ability to vary dynamics through touch.

Cristofori's instrument remained unknown until Scipione Maffei wrote an article about it in 1711, including a diagram. This article was translated and widely shared, inspiring future piano builders like Gottfried Silbermann, who added the forerunner of the modern sustain pedal. This pedal lifts all dampers, allowing notes to continue sounding after the keys are released. Silbermann showed Johann Sebastian Bach one of his early pianos in the 1730s, but Bach disliked it. Later, Bach approved of a revised instrument and helped sell Silbermann's pianos.

Piano making grew in the late 18th century with the Viennese school, including Johann Andreas Stein, Nannette Streicher, and Anton Walter. Viennese pianos used wooden frames, two strings per note, and leather-covered hammers. Some had black natural keys and white accidental keys, opposite of modern pianos. Wolfgang Amadeus Mozart composed music for these instruments, and replicas are used today for authentic performances. Mozart-era pianos had a softer tone and less sustain than modern or English pianos. The term "fortepiano" now refers to these early instruments and their modern copies.

From about 1790 to 1860, the piano underwent major changes, leading to the modern design. This was driven by composers and pianists who wanted a louder, more sustained sound, made possible by the Industrial Revolution, which provided materials like high-quality piano wire and iron frames. The piano's range expanded from five octaves to seven or more.

Early progress in the late 18th century was led by the Broadwood firm. John Broadwood, Robert Stodart, and Americus Backers designed a grand piano in a harpsichord case by 1777. Their instruments were known for their powerful tone and became larger and louder over time.

Types

Modern pianos have two main types: grand pianos and upright pianos, each with different styles. Other types include specialized and novelty pianos, electric pianos that use electromechanical designs, electronic pianos that create piano-like sounds using oscillators, and digital pianos that use recordings of real piano sounds.

In a grand piano, the frame and strings are horizontal, with the strings running away from the keyboard. The action, which is the system that helps the keys move, is located under the strings and uses gravity to return to its resting position. Grand pianos range in length from about 1.5 to 3 meters (4 feet 11 inches to 9 feet 10 inches). Some sizes have traditional names, such as:

• Baby grand: about 1.5 meters (4 feet 11 inches)
• Parlor grand or boudoir grand: 1.7 to 2.2 meters (5 feet 7 inches to 7 feet 3 inches)
• Concert grand: 2.2 to 3 meters (7 feet 3 inches to 9 feet 10 inches)

Longer pianos with longer strings usually produce richer, fuller sounds and have less inharmonicity. Inharmonicity is how much the extra sounds from a piano string are slightly higher than expected. This happens because the strings are stiff. As a string vibrates, its extra sounds (called harmonics) vibrate slightly away from the ends of the string.

Inharmonicity can also come from imperfections in the strings, like rust on plain strings or dirt in the windings of bass strings. The higher the harmonic, the more it sounds sharp. Pianos with shorter, thicker strings, like small pianos, have more inharmonicity. This makes the tone sound harsher.

Because of inharmonicity, piano tuners stretch octaves, meaning they tune octaves slightly higher than the theoretical perfect octave. If octaves are not stretched, single octaves may sound in tune, but larger octaves (like double or triple octaves) sound too narrow. Stretching octaves on small pianos can create imbalances in the relationships between musical intervals.

In a concert grand piano, the octave stretch is carefully adjusted to keep the harmonic balance even when aligning high notes with harmonics from three octaves below. This allows octaves to sound pure and creates perfect fifths with little or no beating. This gives the concert grand a clear, singing tone, which is why full-size grand pianos are used in concert halls. Smaller grand pianos are better suited for homes and small practice spaces.

Upright pianos, also called vertical pianos, have a vertical frame and strings. The upright piano’s action was invented in London in 1826 by Robert Wornum and became popular for home use. Upright pianos take up less space than grand pianos, making them ideal for homes and practice. The hammers in uprights move horizontally and return to rest using springs, which can wear over time.

Some upright pianos with tall frames and long strings are called "upright grand," but this name is misleading. Modern pianos are sometimes classified by height and action modifications. Upright pianos are generally less expensive than grand pianos and are widely used in churches, schools, and music programs for practice.

• Spinets are very short, with the action located below the keys, operated by vertical wires attached to the back of the keys.
• Console pianos are slightly shorter than studio models and have a compact action with shorter hammers. They usually play better than spinets.
• Studio pianos are about 107 to 114 centimeters (42 to 45 inches) tall and have the shortest cabinet that can fit a full-sized action above the keyboard.
• Anything taller than a studio piano is called an upright.

A toy piano, introduced in the 19th century, uses round metal rods instead of strings to make sound. The US Library of Congress classifies toy piano music under the subject "Toy Piano Scores: M175 T69."

In 1863, Henri Fourneaux invented the player piano, which plays music from paper rolls using pneumatic devices. Modern versions, like the Bösendorfer CEUS, Yamaha Disklavier, and QRS Pianomation, use solenoids and MIDI technology instead of paper rolls.

A silent piano is an acoustic piano with a feature that mutes the strings using a hammer bar, allowing for quiet practice.

In 1801, Edward Ryley invented the transposing piano, which has a lever that shifts the keyboard to change the key of the music being played.

The minipiano, patented by the Brasted brothers in 1934, has a braceless back and a soundboard below the keys. Long metal rods pull levers to make hammers strike strings. The first model, called the Pianette, had tuning pins that extended through the instrument for tuning at the front.

A prepared piano is a piano with objects placed inside to change its sound, such as rubber, paper, or metal. These modifications are specified in the music scores.

Some Viennese fortepianos had percussion effects activated by levers, used in pieces like Mozart’s Rondo alla Turca.

A pedal piano has a pedal keyboard at the base, played with the feet. It may use the existing bass strings or have its own set of strings and hammers. Pedal pianos are used to practice pipe organ music at home or for performances.

In 1920, Wadia Sabra had a microtone piano made by Pleyel. Later, Abdallah Chahine created a quartertone "Oriental piano" with help from Austrian Hofmann.

With technological advances, amplified electric pianos (1929), electronic pianos (1970s), and digital pianos (1980s) were developed. Early electric pianos used metal strings with magnetic pickups, amplifiers, and speakers. Popular electric pianos in the 1960s and 1970s, like the Fender Rhodes, used metal tines instead of strings and electromagnetic pickups.

Construction and components

Pianos have more than 12,000 separate parts that support six main functions: the keyboard, action (which includes hammers, hammer shanks, and whippens), dampers and their underlevers, bridges, soundboard, and strings. Many parts are made from materials chosen for their strength and durability. This is especially true of the outer rim, which is often made of hardwood like hard maple or beech. The rim’s large size helps the soundboard vibrate freely. Harold A. Conklin explained that a strong rim helps keep vibrational energy in the soundboard instead of letting it escape into other parts of the piano, which do not transmit sound well.

Hardwood rims are usually made by layering thin, flexible strips of hardwood. These strips are glued and bent into shape. This method was developed by C.F. Theodore Steinway in 1880 to save time and money during production. Before this, rims were made from solid wood pieces joined together, a method used by European makers until the 20th century. Bösendorfer, an Austrian piano maker, uses solid spruce for its inner rims, the same wood as the soundboard. Their "resonance case principle" allows the frame to vibrate more freely with the soundboard, creating a richer and more complex sound.

The thick wooden posts on the underside (for grand pianos) or back (for uprights) help keep the rim stable. These posts are made of softwood for strength. The need for strong materials, like thick hardwood and metal, makes pianos heavy. Even a small upright piano can weigh 136 kg (300 lb). The Steinway concert grand (Model D) weighs 480 kg (1,060 lb). The largest piano available on the market, the Fazioli F308, weighs 570 kg (1,260 lb).

The pinblock, which holds the tuning pins, is another part where strength is important. It is made of hardwood like hard maple or beech and is layered for durability. Piano strings, also called piano wire, are made of high carbon steel. They must withstand years of tension and force. Strings are manufactured to have nearly the same diameter, as any differences can cause sound problems. Bass strings are made of a steel core wrapped with copper wire to increase their weight while keeping them flexible. If all strings were single (monochords), the heavy bass strings would overpower the higher notes. To balance this, makers use two strings (bichords) in the tenor range and three strings (trichords) in the treble range.

The plate (harp) or metal frame of a piano is usually made of cast iron. A heavy plate is beneficial because the strings vibrate from both ends of the plate. A weak plate would absorb too much vibration, reducing the sound quality. While some manufacturers use cast steel, most prefer cast iron because it is easier to shape, more flexible, and less likely to deform. Plate casting requires precision because the iron shrinks by about 1% during cooling. To make the plate look good, makers polish, paint, and decorate it. Plates often include the manufacturer’s logo.

In the 1940s, Alcoa worked with Winter and Company to create pianos with aluminum plates to make them lighter. These plates were not widely accepted and were later stopped. Before this, an aluminum piano was used on the airship Hindenburg.

Most parts of the piano action are made from hardwood like maple, beech, or hornbeam. Since World War II, some makers have also used plastics. Early plastics used in the 1940s and 1950s became weak after many years. In 1961, Steinway used Teflon in some parts of its Permafree grand action instead of traditional wool cloth bushings. This experiment was stopped in 1982 because Teflon caused too much friction and looseness, leading to problems like "clicking." More recently, Kawai used carbon fiber reinforced plastic for action parts, and Wessell, Nickel and Gross created composite parts. These materials have shown promise, but it will take many years to know if they last as long as wood.

In most pianos except the lowest quality, the soundboard is made of spruce boards glued together along the side grain. Spruce is strong and lightweight, which helps the soundboard vibrate well. High-quality makers use spruce with tight grain patterns, carefully dried over time. This is the same material used in good acoustic guitars. Low-cost pianos often use plywood soundboards.

Piano hammers must be soft enough to avoid creating very loud, high-pitched sounds. They must also be light enough to move quickly when a key is pressed but strong enough to hit the strings hard for loud playing. In the early days, keys were made from sugar pine. Today, they are usually made from spruce or basswood. Spruce is used in high-quality pianos. Black keys were traditionally made from ebony, and white keys were covered with ivory. Because ivory is now rare and protected, most makers use plastic instead. Ivory is also more likely to chip than plastic. Some legal ivory is still available, but Yamaha developed a plastic called Ivorite to look and feel like ivory.

Most modern pianos have 52 white keys and 36 black keys, totaling 88 keys (seven octaves plus a minor third, from A0 to C8). Some older pianos have only 85 keys (seven octaves, from A0 to A7

Mechanics

When a piano key is pressed, a series of steps happens to create sound. First, the key lifts the "wippen" mechanism, which pushes the jack against the hammer roller (or knuckle). This action raises the lever that holds the hammer. At the same time, the key lifts the damper. When the hammer hits the string, it quickly moves away, letting the string vibrate and produce sound. When the key is released, the damper returns to the string, stopping the vibration and ending the sound.

The piano strings themselves do not create loud sounds on their own. Instead, their vibrations travel to a large soundboard, which moves air and turns the energy into sound. The bridge, which is shaped irregularly and not centered, helps the soundboard vibrate strongly across all frequencies. The damper remains raised until the key or sustain pedal is released, allowing the note to continue.

Three factors affect the pitch of a vibrating string:
– Length: If all other factors are the same, a shorter string creates a higher pitch.
– Mass per unit length: If all other factors are the same, a thinner string creates a higher pitch.
– Tension: If all other factors are the same, a tighter string creates a higher pitch.

A vibrating string divides into smaller parts that vibrate at the same time. Each part creates its own pitch, called a partial. A string has one main pitch, called the fundamental, and a series of partials. The most harmonious sound occurs when one pitch is exactly twice the frequency of another.

For a repeating wave, the velocity (v) equals the wavelength (λ) multiplied by the frequency (f):
v = λ × f

On a piano string, waves bounce off both ends. These bouncing waves combine to form a standing wave pattern, but only for specific wavelengths: λ = 2L, L, 2L/3, L/2, …, or λ = 2L/n, where L is the string’s length. This means the only frequencies produced on a single string are f = nv/(2L). The quality of sound, called timbre, depends on the mix of these harmonics. Different instruments produce different harmonic patterns for the same pitch. Real strings vibrate at harmonics that are not perfect multiples of the fundamental, causing slight inharmonicity. This adds richness to the tone but makes tuning more difficult across the instrument’s range.

Striking a piano key harder increases the wave’s amplitude, making the sound louder. From very soft (pp) to very loud (ff), the hammer’s speed changes by almost 100 times. The time the hammer touches the string shortens from 4 milliseconds at pp to less than 2 milliseconds at ff. If two strings tuned to the same pitch are struck together, their vibrations combine to create a louder, shorter sound. If the vibrations are out of sync, they cancel each other slightly, creating a softer, longer sound.

Maintenance

Pianos are heavy and powerful, yet delicate instruments. Over time, professional piano movers have created special methods for moving both grand and upright pianos safely, ensuring the piano's case and internal parts are not damaged. Pianos require regular tuning to maintain the correct pitch. The hammers inside pianos are adjusted to account for the gradual hardening of the felt, and other parts also need regular checks and adjustments. Pianos must be maintained to ensure the felt hammers and key mechanisms work correctly. Older or worn-out pianos can be restored by piano rebuilders. Eventually, the strings must be replaced. By replacing many parts and adjusting them, older pianos can perform as well as new ones.

Piano tuning involves adjusting the tension of the piano's strings using a special tool to align the intervals between the notes so the instrument is in tune. While guitar and violin players usually tune their own instruments, pianists often hire a piano tuner, a trained technician, to do the work. The piano tuner uses specialized tools. The term "in tune" in piano tuning does not mean a fixed set of pitches.

Fine piano tuning carefully examines how each note interacts with all other notes in the chromatic scale, which varies for every piano. This process requires slight adjustments to pitches that differ from standard theoretical measurements. Pianos are typically tuned to a modified version of a system called equal temperament. In all tuning systems, each pitch is based on its relationship to a chosen fixed pitch, usually the internationally accepted concert pitch of A4 (the A above middle C). The term A440 refers to the widely accepted frequency of this pitch: 440 Hz.

The relationship between two pitches, called an interval, is the ratio of their frequencies. Two intervals are perceived as the same if the pairs of pitches share the same frequency ratio. The simplest intervals to identify and tune are called "just" intervals, which have simple whole-number ratios. The term "temperament" describes a tuning system that adjusts just intervals (such as the perfect fifth, with a ratio of 3:2) to meet another mathematical requirement. In equal temperament, a fifth is adjusted slightly by lowering its upper pitch or raising its lower pitch. A temperament system is also called a set of "bearings."

Tempering an interval causes it to "beat," which is a fluctuation in sound intensity caused by interference between two close but unequal pitches. The speed of beating depends on the frequency differences of harmonics that overlap or nearly overlap. Piano tuners use their ears to "stretch" the tuning of a piano to make it sound in tune. This involves tuning the highest-pitched strings slightly higher and the lowest-pitched strings slightly lower than what a mathematical frequency table (where octaves are created by doubling the frequency) would suggest.

Playing and technique

The piano, like other musical instruments, can be played using written music, by listening to others, or by creating music on the spot. While some folk and blues pianists learned without formal training, classical and jazz musicians often study through established teaching methods. These include exams before college, degrees from universities and music schools, and advanced qualifications such as Bachelor of Music, Master of Music, and Doctor of Musical Arts in piano. Piano techniques changed as the instrument evolved from older forms like the harpsichord and clavichord to the fortepiano, and later to the modern piano. Over the 19th and 20th centuries, changes in music styles, audience preferences, and the rise of highly skilled performers influenced how piano techniques developed. Many teachers and performers emphasize that piano playing involves both physical skills and mental or emotional aspects. Notable piano technique methods include those created by Dorothy Taubman, Edna Golandsky, Fred Karpoff, Charles-Louis Hanon, and Otto Ortmann.

Many classical composers, such as Haydn, Mozart, Schubert, and Beethoven, wrote music for the fortepiano, which was different from today’s modern piano. Even Romantic-era composers like Franz Liszt, Frédéric Chopin, Clara and Robert Schumann, Fanny and Felix Mendelssohn, and Johannes Brahms composed for pianos that were not the same as modern instruments. Today, musicians may adjust how they play older compositions to match the sound and style of historical instruments.

During Beethoven’s later years, the fortepiano began to resemble the modern piano. By the late 19th century, modern pianos were widely used. These had more keys than the fortepiano, adding about 30 keys to expand the range of low and high notes. Mass production of upright pianos made them more affordable, allowing middle-class people to own them. Pianos were played in music halls and pubs during the 19th century, either by soloists or with small dance bands. Similar to how harpsichordists accompanied singers and dancers, pianists took on this role in the late 18th and 19th centuries.

In the 19th century, American musicians, especially African-American composers, created new music styles using the modern piano. Ragtime, popularized by Scott Joplin, became widely known by 1900. Ragtime was later followed by Jazz piano, which introduced new techniques like boogie-woogie rhythms and Shearing voicing. George Gershwin’s Rhapsody in Blue combined jazz piano with orchestral music.

A technique called comping, used to accompany jazz vocalists, was popularized by Duke Ellington. Honky-tonk music, with its unique piano rhythms, also gained popularity during this time. Bebop, a more complex jazz style, developed with pianists like Thelonious Monk and Bud Powell. In the late 20th century, Bill Evans blended classical techniques with jazz. In the 1970s, Herbie Hancock became famous for combining jazz with urban music styles like jazz-funk and jazz-rock.

Pianos have also played a key role in rock and roll and rock music. Artists like Jerry Lee Lewis, Little Richard, Keith Emerson, Elton John, Ben Folds, Billy Joel, Nicky Hopkins, Rick Wakeman, Freddie Mercury, and Tori Amos used pianos in their music. In 2023, Freddie Mercury’s Yamaha baby grand piano, used to compose Bohemian Rhapsody, sold for £1.7 million, a record for a composer’s piano. Modernist composers like John Cage and Philip Glass have also written music for the modern grand piano.

The piano was introduced to Burma in the mid-19th century and adapted by local musicians. Burmese pianists use a special technique involving both hands playing a single melody line with added musical details. This method, inspired by traditional Burmese timekeeping, is used to perform Mahāgīta compositions. Many Burmese pianists, such as Sandayar Hla Htut and Sandayar Chit Swe, use the word sandaya (meaning "piano") in their titles.

Role

The piano is an important instrument in many types of Western music. It is used for playing alone, for focusing on melodies, and for supporting other instruments. Pianos can be played by one person, with a singer or another instrument, in small groups like bands or chamber music ensembles, and in large groups like orchestras or big bands. Many composers and songwriters know how to play the piano because the keyboard makes it easier to test complex melodies and harmonies, as well as to play multiple independent melodies at the same time. Pianos are also used by composers who create music for movies and television, as the wide range of the piano allows them to try out melodies and bass lines, even if the final music will be played by other instruments.

Bandleaders and choir conductors often learn to play the piano because it helps them learn new songs and lead performances. Many conductors are trained in piano because it allows them to play simplified versions of the symphonies they conduct, helping them practice and understand the music better. The piano is an important tool in music education at schools, colleges, and universities. Most music classrooms and practice rooms have a piano. Pianos are used to teach music theory, music history, and music appreciation classes. Even teachers who do not play the piano may have one in their office.