There are several kinds of data that may compromise users’ anonymity online. The most important are as follows, but are not limited to these:
- IP address: An IP address is provided by an internet service provider (ISP). It knows the identity of the person that used their identity to make the contract.
- System data (‘fingerprints’): While accessing the internet, your computer or smartphone sometimes has to send technical information about the system like software version, language settings, hardware information or screen size. This information can reveal your identity or at least work as an identifier, as the composition of different data is often unique.
- Account information: If users sign up for a service, they mostly have to provide certain personal information like email addresses, telephone numbers and bank information for the purpose of billing.
- User provided information: Every content that users provide on the internet might be individualised, and therefore be linked to an identity. This can included messages, shared photos or metadata about users’ activities. For example, using an anonymisation tool would be useless if a user reveals his or her name in an unencrypted message.