A keyboard instrument is a musical instrument played with a musical keyboard. Keyboard instruments can be wind instruments, string instruments, percussion instruments, or electronic instruments.

The most popular keyboard instruments are probably the piano and the synthesizer.

String keyboard instruments:

• Clavichord
• Harpsichord—may also be called a cembalo or virginal
• Piano
• Tangent Piano — also known as "Tangentenflugel"

Wind keyboard instruments:

• Accordion
• Melodica
• Harmonium
• Organ

Electronic/electromechanical keyboard instruments:

• Sampler
• Synthesizer
• Ondes Martenot
• Electric piano
  • Rhodes piano also known as a Fender-Rhodes piano
  • Clavinet
  • Pianet
• Mellotron
• Chamberlin
• MIDI keyboard controller

Percussion instruments:

• Carillon
• Celesta (struck metal plaques)
• Toy piano

History of keyboard instruments

Among early keyboard instruments are the organ, the clavichord, and the harpsichord. Early keyboard instruments that failed to gain widespread popularity are the geigenwerk and the tangent piano. The organ is accepted as the first keyboard instrument, appearing in the 5th century BCE. The organ was water powered and aptly named the hydraulis. Developments over the following two millenia contributed to the familiar 'cathedral organ,' which features massive pipes and thousands of stops. Between its invention and the beginning of the renaissance, the organ remained the only keyboard instrument. Often, the organ didn't feature a keyboard at all, rather buttons or large levers which were operated by a whole hand. Almost every keyboard until the 15th century had 7 naturals to each octave. The clavichord appeared during the mid-14th century and the harpsichord shortly thereafter. During their development, the b flat was added to the keyboard in order to remedy the discordant b diminished chord, which has three natural skips in succession. Also added was the e flat, then the rest of the sharps, f#, c#, and G#, in that order. The organ, harpsichord, and clavichord enjoyed widespread popularity for four centuries. Early electromechanical instruments, predecessors of the synthesizer, appeared in the early 20th century.