Harmonium is a type of reed organ that generates sound with bellows. It blows air through reeds, producing musical notes. Harmonium sounds like an accordion. It was invented in Europe at Paris in 1842 by Alexandre Debain .

Harmonium is also known as “Peti” or “Baja”. It is an European instrument which was imported in the 19th century. Although this is an European invention, it has evolved into a truly bi-cultural instrument. The keyboard is European , but it has a number of drone reeds which are Indian.

The body is the box that houses the various parts of the harmonium. There are two basic styles. One is simply a box with everything in a fixed position. Another collapses down into a suitcase style of enclosure. Bellows are the pumps which force air through the instrument. The keys known in India as “Chabi” are the small wooden controls that the performer fingers to play the music. There are black and white keys. The cover is a small piece of wood of cloth or glass. It covers the working of the harmonium.

The main stops are a series of valves which control the way that air flows in the instrument. The drone stops control the flow of air over un-keyed reeds. The handles allow for easy transport of the harmonium.

There are two common sitting positions, a standard position and the other used by qawwali singers. The harmonium can also be played standing and walking. In this case the harmonium is slung by a strap around the neck. This however, seems to be limited to beggars that one may encounter.

Harmoniums are largely used in Indian genre of music for Bhajans, film music, folk music, ghazal, Kathak dance, qawwali, kirtan, shabad, thumri and kheyal. It is a staple of vocal north Indian classical musical concerts. It was widely used in Parsi and Marathi stage shows. There is at least one harmonium in any mandir or gurudwara around the world. It is commonly accompanied by table as well as dholak. Almost all qawwals use the harmonium as their solo musical accompaniment.

Harmoniums became quite popular in western popular music since 1960‘s. It was embraced to certain extent by European and American composers of classical music. It played a significant part in the new rise of Nordic folk music in Finland in 1970. A harmonium could be found in the most schools where the band met, and it became natural for the bands to include a harmonium in their set up.