Olfactory notes refer to the distinct scents that make up a fragrance, often categorized into three main layers: top, middle, and base notes. The top notes are the initial scents perceived upon application, usually light and fresh. Middle notes, or heart notes, emerge after the top notes fade and provide the fragrance's main character. Finally, base notes are the deeper, richer scents that linger the longest, adding depth and warmth to the overall aroma. These notes are essential in the creation of perfumes and are carefully blended to achieve a harmonious scent profile. Perfumers often use a variety of natural and synthetic ingredients to craft these notes, drawing from sources like flowers, fruits, and spices. Understanding olfactory notes helps consumers appreciate the complexity of fragrances and choose scents that resonate with their personal preferences.