Virtual Redundancy Protocol (VRRP) is a way to make sure that data transfers don't get lost in transmission. The best thing about it is that it requires very little extra equipment.
The primary focus of VRRP is data that transmitted over a local area network (LAN). Traditionally, such data transfers are made using a router. In the best tradition of the American Federal Government, it is a good policy to provide redundant transfer systems. In other words, use a backup router to make sure that the data transfer goes through.
One way to make sure that this backup works on a network is to use the Internet. All routers involved in the data transfer are tied in to a virtual Internet Protocol (IP) address. In the case of VRRP, however, it's not just one router that is the backup; rather, only one router is the master, and all the rest are backups.
This system is possible because every router is tied in to the virtual IP address via VRRP. If the master router fails, then one by one the other routers become the master. Whichever one assumes the virtual IP address first is the new master. If that master fails, then another of the connected routers assumes the master duties.
The more routers that are connected to the network, the more opportunities the network has of protecting the data transfer. If every single router in the network chain fails, then the problems associated with that failure are probably larger than the loss of the data being transferred. Such catastrophic failure is not likely, however. What is much more likely is the failure of one router, which is replaced by another via VRRP.
VRRP is a generic standard of connectivity. Some computer system giants have their own similar systems. Cisco Systems has Hot Standby Router Protocol (HSRP). Digital Equipment Corporation has IP Standby Protocol (IPSTB). These acronyms are different ways of saying the same thing. They are both VRRP.