Track users in all their most intimate actions is the intent of the most hardened and marketing technologies that provide anonymity are one of the few banks that have been erected to curb the urge to control individual in order to calculate and correct the sales strategies. Tor is a project developed by the Electronic Frontier Foundation which consists of a software capable of lose track of the origin of network communications. The technique used is to push through such communications through a network of servers that will 'bounce' the information, called 'onion routers', ie 'onion-router', which, just like the layers of the common vegetable protect the 'user from being traced. The software is available both as a client and a server, both cross-platform (Windows, Unix, MacOS X) and promises not only in the anonymity of web browsing, but also in its publishing, in instant messaging, chat rooms on IRC, in communications encrypted SSH and so on. The 'traffic analysis' (traffic analysis), raptures when you bask the online marketing experts, as well as network administrators patients megalomania, so goes belly up, it is impossible (even for the same onion routers) to establish the origin of the demands of their data. The mechanisms of the network, that is the passage through the server, they are so exploited to keep out all prying eyes, both authorized and unauthorized, in one of the few concrete revenge of privacy.