Middle notes, also known as heart notes, are the scents that emerge after the initial top notes of a fragrance have evaporated. They typically appear about 10 to 30 minutes after application and can last for several hours. These notes are crucial in defining the character of a perfume, as they create a bridge between the top and base notes. Common middle notes include floral scents like rose and jasmine, as well as spices like cinnamon and nutmeg. They provide depth and richness to the fragrance, making it more complex and appealing. The balance of middle notes can significantly influence the overall impression of a perfume.