What musical time period was Franz Joseph Haydn in?

Franz Joseph Haydn was primarily active during the Classical period of music, which spanned from the mid-18th century to the early 19th century. He is often referred to as the "Father of the Symphony" and the "Father of the String Quartet" due to his significant contributions to these genres. Haydn's work laid the foundation for later composers, including Mozart and Beethoven, and he was influential in the development of sonata form and other musical structures characteristic of the Classical style.