How does the Hornbostel-Sachs system classify musical instruments?

The Hornbostel-Sachs system is the standard method used in systematic studies to classify musical instruments based on the physical source of their sound production. Developed by musicologists Erich von Hornbostel and Curt Sachs, the system expands upon an earlier fourfold division by Victor-Charles Mahillon and utilizes a hierarchical structure similar to botanical classification.1

The system categorizes instruments into five primary classes:

• Idiophones: Instruments made of sonorous material that vibrates to produce sound (e.g., bells, rattles).1
• Membranophones: Instruments where a stretched skin or membrane vibrates to produce sound, such as drums.1
• Aerophones: Instruments where sound is produced by a vibrating column of air, commonly known as wind instruments.1
• Chordophones: Instruments that produce sound through vibrating strings.1
• Electrophones: A later addition consisting of instruments where vibration is produced by oscillating electric circuits.1

Because the system is designed to organize museum collections, it is considered an arbitrary, albeit highly influential, framework that may differ from how musicians categorize instruments based on playing techniques.1