Celtic harps are also known as "lever," "Irish" or "folk" harps. The lever harp is an older form than the pedal harp, which is the big golden harp you see at an orchestral concert. The lever harp is made with levers along the top of the arch, hence the name. There is a lever for each string. When the lever is manually raised, it also raises the pitch of the string by half a step. In this way, the harpist is able to play in different keys. However, the harpist must take her hands from the strings in order to raise the levers, and the lever must be raised for each string that is changing pitch. This makes playing some modern music, which changes key often in the middle of the piece or has many single-note pitch changes throughout the piece, difficult and sometimes impossible to play on a lever harp. As music became more complex, harp makers looked for a way for the harpist to change the pitch of the strings without taking the hands away from their playing position. The French developed the pedal harp. Pedals at the base of the harp allowed the harpist to raise the pitch of all the strings that are a particular note (all the "F" strings, for example) at one time. This expanded the harp repertoire immensely, and it is the reason you see pedal harps, rather than lever harps, in the orchestra pit.