Advanced Onion Router is designed to be a client for TOR network and intended to be an improved alternative for Tor+Vidalia+Privoxy bundle for Windows users. It is able to "force" a program and its plugins to use the Tor proxy regardless of its configured proxy settings.

Onion Routing is a distributed overlay network designed to anonymize TCP-based applications like web browsing, secure shell, and instant messaging. Clients choose a path through the network and build a circuit, in which each node (or “onion router” or “OR”) in the path knows its predecessor and successor, but no other nodes in the circuit. Traffic flows down the circuit in fixed-size cells, which are unwrapped by a symmetric key at each node (like the layers of an onion) and relayed downstream.