What is HSRP (Hot Standby Router Protocol)?

Hot Standby Router Protocol (HSRP) is a CISCO proprietary protocol. It gives redundancy for a local subnet. HSRP gateways conveys multicast hello messages to different gateways to inform them of their priorities for gateway and current status. HSRP permits to design at least two routers as standby routers and just a solitary router as an active router at a time.