A string quartet is chamber music usually played with two violins, a viola, and a cello. Haydn, called the father of the string quartet, composed 68 string quartet pieces. Furthermore, Mozart, influenced by him, also left many compositions such as the masterpiece "Haydn Quartets". Haydn and Mozart deepened their musical fellowship by performing together. After that, many musicians including Beethoven, Schubert, etc left many pieces in this genre, and many more pieces have been composed and enjoyed ever since.