In-N-Out Burger is a popular fast-food chain based in California, known for its simple menu featuring hamburgers, cheeseburgers, fries, and milkshakes. Founded in 1948 by Harry Snyder and his wife, Esther Snyder, the restaurant emphasizes fresh ingredients and quality food. The chain has a cult following due to its commitment to customer service and the "secret menu," which offers variations like the "Animal Style" burger. With locations primarily in the western United States, In-N-Out Burger has expanded steadily while maintaining its reputation for consistency and quality.