Users like to use pseudonyms on different platforms. These identities can be brought together depending on what information is given there about oneself. So-called de-anonymization is possible if the anonymization or pseudonymization was insufficient. For example, a study on US citizens was published in Nature. Depending on what data was available, the people could be identified. It was 83% for the attributes gender, postal code and birthday, and 99.98% for 15 attributes. It looks similar with New York taxi drivers despite pseudonymized license plates. For this purpose, Chris Whong evaluated a database. Accordingly, it is important what information you share with others.