The main ingredient in traditional Italian pesto is basil, specifically fresh basil leaves. Pesto, a flavorful sauce originating from the Liguria region, typically combines these fragrant leaves with garlic, pine nuts, Parmesan cheese, and olive oil. The ingredients are crushed together to create a thick, green paste, which is used to enhance various dishes such as pasta, sandwiches, and salads. The vibrant flavor of fresh basil is complemented by the richness of olive oil and cheese, creating a unique taste that embodies Italian culinary traditions. Variations of pesto can also include other ingredients like sun-dried tomatoes or nuts.