The modern concert harp produces a rich, ringing sound when the harpist plucks the strings or brushes her hand over them. As is heard in the beginning of the second movement of Caesar Franck's Symphony in D minor, the harp's sound is less dry than that of plucked pizzicato strings.
Like individual keys on the piano, each individual string on the harp produces a different note. The instrumentalist can press one of several pedals at the base of the harp to change the notes that the strings produce, and thus change the key. The range of many concert harps extends from C1 to G7.