 This high-speed network, unrestricted to academic users, became a backbone to which regional networks would be connected.Initially a 56-kbit/s network, traffic on the network grew exponentially; the links were upgraded to 1.5-Mbit/s T1s in 1988 and to 45 Mbit/s in 1991.The NSFNet was a major milestone in the development of the Internet and its rapid growth coincided with the development of the World Wide Web.