The "Haydn Quartet" refers to a group of string quartets composed by Joseph Haydn, an influential Austrian composer of the Classical period. Haydn is often called the "father of the string quartet" due to his significant contributions to the genre, which includes over 70 quartets. These works are characterized by their innovative structures, rich harmonies, and engaging dialogues between instruments. The quartets typically feature two violins, a viola, and a cello, allowing for a blend of melodic and harmonic interplay. Haydn's quartets laid the groundwork for later composers, including Ludwig van Beethoven and Wolfgang Amadeus Mozart, who expanded on his ideas and techniques in their own compositions.