Blue cheese is a type of cheese that is typically made from cow's milk, although it can also be made from sheep's milk or goat's milk. The cheese is characterized by its blue or green veins, which are created by the introduction of Penicillium cultures during the cheesemaking process. The exact origin of blue cheese is not clear, but it is believed to have been first created in France in the 7th century. The cheese was likely discovered by accident, when cheese was stored in damp caves, allowing the Penicillium cultures to grow and develop. Today, blue cheese is made in many different countries and regions around the world, and there are many different varieties and styles of blue cheese available. Some of the most popular types include Roquefort, Gorgonzola, and Stilton. Blue cheese is often used in cooking and can add a unique flavor and texture to a wide range of dishes.