Instruments with a keyboard have been very popular for many hundreds of years, as they are relatively easy to learn and can play both melody and harmony together. 

In the sixteenth century, the harpsichord and the clavichord were very popular.  On the harpsichord, a string is plucked when a key is depressed, while on the clavichord, a string is struck.  Both instruments produce a delicate and small sound. The pipe organ was became widely used in the eighteenth century.  Its ability to produce a wide range of sounds, which were produced by forcing air through the instrument's pipes inspired grand and expressive music.  It was developed for worship, and can still be seen in many churches. 

The piano, which was invented in the early eighteenth century, gradually began to replace the harpsichord as the most popular keyboard instrument.  It is often classified as a percussion instrument, because sound is produced when hammers strike the strings within the instrument.  It possesses a wide range of expression, capable of producing tender, intimate melodies, as well as percussive and brutal sounds.