An electric piano is a musical instrument which produces sounds when a performer presses the keys of a piano-style musical keyboard. Pressing keys causes mechanical hammers to strike metal strings, metal reeds or wire tines, leading to vibrations which are converted into electrical signals by pickups (either magnetic, electrostatic or piezoelectric) which are then connected to an instrument amplifier and loudspeaker to make a sound loud enough for the performer and audience to hear. Unlike a synthesizer, the electric piano is not an electronic instrument. Instead, it is an electro-mechanical instrument. Some early electric pianos used lengths of wire to produce the tone, like a traditional piano. Smaller electric pianos used short slivers of steel to produce the tone (a lamellophone with a keyboard & pickups). The earliest electric pianos were invented in the late 1920s; the 1929 Neo-Bechstein electric grand piano was among the first. Probably the earliest stringless model was Lloyd Loar's Vivi-Tone Clavier. A few other noteworthy producers of electric pianos include Baldwin Piano and Organ Company and the Wurlitzer Company.
Early electric piano recordings include Duke Ellington's in 1955 and Sun Ra's India as well as other tracks from the 1956 sessions included on his second album Super Sonic Jazz (a.k.a. Super Sonic Sounds). The popularity of the electric piano began to grow in the late 1950s after Ray Charles's 1959 hit record "What'd I Say", reaching its height during the 1970s, after which they were progressively displaced by more lightweight electronic pianos capable of piano-like sounds without the disadvantages of electric pianos' heavy weight and moving mechanical parts. Another factor driving their development and acceptance was the progressive electrification of popular music and the need for a portable keyboard instrument capable of high-volume amplification. Musicians adopted a number of types of domestic electric pianos for rock and pop use. This encouraged their manufacturers to modify them for stage use and then develop models primarily intended for stage use.
Digital pianos that provide an emulated electric piano sound have largely supplanted the actual electro-mechanical instruments in the 2010s, due to the small size, low weight and versatility of digital instruments, which can produce a huge range of tones besides piano tones (e.g., emulations of Hammond organ sounds, synthesizer sounds, etc.). However, some performers still perform and record with vintage electric pianos. In 2009, Rhodes produced a new line of electro-mechanical pianos, known as the Rhodes Mark 7, followed by an offering from Vintage Vibe.