A technique for anonymous communication over a computer network where messages are encapsulated in layers of encryption (hence the onion analogy). Encrypted data is sent through a series of nodes called onion routers, each of which “peels” away a single layer, uncovering the data’s next destination. When the final layer is decrypted, the message arrives at its destination. The sender remains anonymous because each intermediary knows only the location of the immediately preceding and following nodes.