The Hydraulis is an ancient musical instrument, often considered a precursor to the modern organ. It was invented in ancient Greece around the 3rd century BCE and used water to create air pressure, which allowed for the production of sound. The instrument typically featured a series of pipes and a keyboard, enabling musicians to play melodies. The Hydraulis was commonly used in public performances and events, showcasing its significance in ancient culture. Its design influenced later keyboard instruments, including the organ and the piano. The Hydraulis represents an important development in the history of music technology.