Anonymity is derived from the Greek word ἀνωνυμία, anonymia, meaning “without a name” or “namelessness”. In colloquial use, anonymity typically refers to the state of an individual’s personal identity, or personally identifiable information, being publicly unknown. There are various situations in which a person might choose to withhold their identity. Acts of charity have been performed anonymously when benefactors do not wish to be acknowledged.
Most commentary on the Internet is essentially done anonymously, using unidentifiable pseudonyms. While these usernames can take on an identity of their own, they are frequently separated and anonymous from the actual author. According to the University of Stockholm this is creating more freedom of expression, and less accountability. Wikipedia is collaboratively written mostly by authors using either unidentifiable pseudonyms or IP address identifiers, although a few have used identified pseudonyms or their real names.
However, the Internet was not designed for anonymity: IP addresses serve as virtual mailing addresses, which means that any time any resource on the Internet is accessed, it is accessed from a particular IP address. This address can be mapped to a particular Internet Service Provider (ISP), and this ISP can then provide information about what customer that IP address was leased to. This does not necessarily implicate a specific individual (because other people could be using that customer’s connection, especially if the customer is a public resource, such as a library), but it provides regional information and serves as powerful circumstantial evidence.