is a backwards-compatible modification to the TCP protocol which adds opportunistic encryption. It's designed to hamper and detect large-scale wiretapping and corruption of TCP traffic on the Internet.

TLS is the solution to protecting sensitive information. However, there's room for a low setup cost protocol to protect the bulk of traffic which isn't currently encrypted. It can't stop a focused attack, but it can assuage untargeted, dragnet sniffing of backbones and spoofing of RST packets.