Opera seria is a genre of Italian opera that emerged in the early 18th century, characterized by its serious themes and noble characters. It often features historical or mythological subjects, focusing on moral dilemmas and emotional conflicts. The music is typically structured with arias, recitatives, and orchestral interludes, showcasing the vocal talents of the performers. The genre was popularized by composers like George Frideric Handel and Antonio Vivaldi, who created works that emphasized dramatic expression and virtuosic singing. Opera seria played a significant role in shaping the development of opera, influencing later styles and composers throughout the 18th and 19th centuries.