So far, we have restricted ourselves to describing anonymity. We could extend these notions to allow for the use of pseudonyms. If two transactions in the system can be linked, then the attributes which allow them to be linked make up a pseudonym. For example, in an author-pseudonymous system, the documents digitally signed by ``Publius'' could all be verified as ``belonging to Publius'' without anyone coming to know who ``Publius'' is in 'real life.'
Both anonymity and pseudonymity protect the privacy of the user's location and true name. Location refers to the actual physical connection to the system. The term ``true name'' was introduced by Vinge [43] and popularized by May[29] to refer to the legal identity of an individual. Knowing someone's true name or location allows you to hurt him or her.
Many different actions can be linked to the same pseudonym, while an anonymous system allows no linking at all. This allows the pseudonym to acquire a reputation. Free Haven uses pseudonyms to give each servnet node a reputation; the reputation influences how much data a node can store and provides an incentive to act correctly.