Interior gateway protocols (IGPs) are routing protocols used within a single autonomous system, which is a network or group of networks under a common administration. They help routers communicate and share information about the best paths for data to travel within that system. Common examples of IGPs include Open Shortest Path First (OSPF) and Routing Information Protocol (RIP). IGPs are essential for efficient network operation, as they enable dynamic routing, allowing routers to adapt to changes in the network, such as new devices or link failures. By using IGPs, network administrators can ensure reliable and optimized data transmission across their internal networks.