A username or user ID is a name that a user can use to log on to a computer, website, or program. On the Internet, in conjunction with a secure password, it is usually used to log in to a user account and requires prior registration. In the case of services without a fixed user account, e.g. Internet Relay Chat, the nickname may be the same as the username.
With the many online services, the username can be freely chosen, as long as it has not already been assigned to another user or violates the terms and conditions.
Some services require an email address to uniquely identify a user in order to register a username. To prevent misuse, many services verify the email address provided by the user with a double opt-in procedure. This ensures that the user has access to the mail account of the specified address.
In the meantime, many services recommend adding another security feature to increase the security of the user account. This is also known as two-factor authentication. After authentication by means of a username and password, another characteristic is checked. This can be, for example, a PIN sent via SMS.
If the use of the civil name as a username is obligated either by the operator or by the state, this is referred to as a real name compulsion or real name obligation.
A concrete example of this is the debate about the use of pseudonyms on the social network Facebook. Following a lawsuit filed by few users, many Courts has ruled that Facebook, whose terms and conditions stipulate an obligation to use real names, must also allow fantasy names. This was triggered by the General Data Protection Regulation, which came into force in 2018, which does not contain any provisions on the use of pseudonyms and thus leaves open whether platform operators can require the use of real names when choosing a username.
The consequences of an inadequately protected username and user account can be far-reaching in the event of misuse. For example, attackers can use illegally acquired user accounts to order goods, take out subscriptions or carry out similar actions under a false identity.