The Onion Router a.k.a Tor is designed to provide anonymous communication between node A and B. The TOR project was designed in 1995 by the US Naval Research Laboratory.
Tor is 17 years old
The TOR project is financed by the American Ministry of Defence and the Eletronic Frontier Foundation. TOR was created to ensure communication between government agencies.
Now a days TOR is an open source project and it is a free application that uses several plugins to help users world wide to become anonymous.
There are four TOR configurations that TOR can use to communicate:
The "client" is the user of TOR itself,
The 'relays' are a hatch and are fully encrypted on both sides
- Bridge Relays
Bridge relays "are censored for users who do not have access to the TOR network having known such relays are blocked by an ISP (Internet Service Provider) to provide it access to the TOR network
End-nodes function entirely as a conduit and are only from one side encrypted and a final end-node or also known as Exit node can log what you do, this end-nodes are often in data center partly because much bandwidth is processed at the End node.
Use these links for more information about the TOR Project: