The harpsichord was the primary keyboard instrument of the Baroque era. Its mechanism is fundamentally different from a piano; when a key is pressed, a small plectrum (traditionally made of quill) plucks the string. This results in a bright, percussive sound with little sustain. Because the plucking force is constant, the player cannot control the volume (dynamics) by touch; every note is the same loudness regardless of how hard the key is struck. To overcome this, many harpsichords have two keyboards (manuals) that can be coupled together to play multiple strings per key for a louder sound. The instrument fell out of favor once the piano was invented, as composers like Mozart and Beethoven demanded more expressive dynamic control. However, the harpsichord remains essential for the performance of works by Bach, Handel, and Scarlatti, providing the rhythmic 'crispness' that defines the Baroque sound.