A harmonium is a musical instrument that produces sound by forcing air through reeds. It typically has a keyboard similar to a piano, allowing musicians to play melodies and chords. Harmoniums are often used in various music genres, including Indian classical music and devotional music, due to their rich, warm tones. The instrument is played by pumping a foot-operated bellows, which supplies air to the reeds. Harmoniums can vary in size and design, with some featuring additional stops to modify the sound. They are popular in many cultures and are appreciated for their portability and ease of use.