The harp is plucked string instrument of very ancient lineage. It is believed to have originated in Mesopotamia as early as 3500 BCE. The harp consists of an open frame with a graduated series of strings stretched over it. To play the harp the strings are plucked with the fingers.
On the modern orchestral harp the strings are not tuned to the chromatic scale like they are on the piano, but instead tuned to the notes of the C flat Major scale. Seven pedals at the base of the harp are then used to alter the pitch of certain strings allowing the player to play in different keys. Each pedal has two notches which raise the pitch of the strings by a semitone and a tone respectively. By using the various pedals and notches in combination the harp can be tuned to all the major and minor keys, and more. The range of the harp is usually about five and a half octaves.
Chords on a harp are normally played with each note of the chord sounded individually but in rapid succession, a technique known arpeggio (arpa being Italian for Harp). The characteristic sweeping sound of the harp comes from the player passing their hands quickly over the strings in a long strumming fashion. This sweeping effect can be used on many types of scale but because of how the strings are tuned, and the way the pedals work, it will only work for scales with seven notes (in some cases less) in the octave. Chromatic scales, therefore, cannot be played this way on the harp.
The harp has been used as a solo instrument in Wales for many centuries and was popular in England during the Victorian period. It was used frequently in orchestras during the 17th century but went out of fashion until great Romantic composers such as Berlioz, Wagner, Strauss, and Mahler began to make effective use of it once more.
Several types of harp exist other than the standard orchestral harp. These include the Chromatic Harp, Double Harp, Clarsach, Dital Harp, and the Aeolian Harp.