Interior Gateway Protocol (IGP) is a type of routing protocol used in telecommunications networks to exchange routing information within an autonomous system. In the UK market, common IGPs include RIP (Routing Information Protocol), OSPF (Open Shortest Path First), and EIGRP (Enhanced Interior Gateway Routing Protocol). These protocols are crucial for ensuring efficient communication and data transfer within a network, helping to determine the best path for data packets to reach their destination. By utilizing IGPs, telecom operators in the UK can optimize network performance, enhance reliability, and improve overall quality of service for their customers.