Since it was impossible to “follow” a user based on log files, Lou Montulli invented the HTTP cookie in 1994. This enabled website owners to place a small text file on a user’s hard disk and recognize him again when another page of the site is requested, the basis for building a web store, for example. Until today, cookies are a basic means to recognize users although they have several disadvantages:
- They can be deleted, and they are deleted.
- They do not represent a user but a user account on a single machine.
Cookies are differentated into 1st party and 3rd party cookies. The webserver visited by a user is allowed to set a 1st party cookie; if the web page includes a reference that tries to set a cookie from a different web server, this would be regarded as a 3rd party cookie; 3rd party cookies often are blocked. As a consequence, advertising companies have a huge interest in setting 1st party cookies.