Terminology
A number of non-harp-like instruments are colloquially referred to as "harps". Chordophones like the aeolian harp, (wind harp) and the autoharp (with the piano and harpsichord) are not harps, but zithers, because their strings are not perpendicular to their soundboard. Similarly, the many varieties of harp guitar and harp lute, while chordophones, belong to the lute family and are not true harps. All forms of the lyre and kithara are also not harps, but belong to the fourth family of ancient instruments under the chordophones, the lyres.
The term "harp" has also been applied to many instruments which are not chordophones. The vibraphone was (and is still) sometimes referred to as the "vibraharp," though it has no strings and its sound is produced by striking metal bars. In blues music, the harmonica is often casually referred to as a "blues harp" or "harp", but it is a free reed wind instrument; not a stringed instrument, and is therefore not a true harp.
Read more about this topic: Harp