Tor: What it is and how it works

Tor is a free software project designed for anonymous communication. The name stands for The Onion Router because it is based on a system that encrypts data in layers, like the skins of an onion.

The initial technology was developed by the U.S. Naval Research Laboratory to help protect military and government communications, although it has been enlarged and improved since then by a network of usually volunteer developers.

The not-for-profit Tor Project oversees and organizes the software. Its largest benefactor is the U.S. State Department, which supports Tor as a way for dissidents in repressive countries to communicate.

Tor is a peer-to-peer network, under which traffic is handed off between independent computer servers, often called nodes, that volunteer to be part of the network.

Tens of thousands of such servers around the world are part of Tor. The Kilton Public Library was one of them.

In technical terms it had a middle-relay server, which hands off data to other servers, rather than an exit relay that would hand it off to end users, said library director, Sean Fleming.