A piano is a versatile musical instrument with keys that produce sound when struck. It is widely used in various music genres, from classical to jazz, and can play both melody and harmony. The piano's rich sound and dynamic range make it a popular choice for solo performances and accompaniment. A string quartet consists of four musicians playing two violins, a viola, and a cello. This ensemble is a staple of classical music, known for its intricate harmonies and interplay between instruments. String quartets often perform original compositions and arrangements, showcasing the unique timbres of each string instrument.