S 2.488 Web tracking

Web tracking refers to the evaluation of user data, for example, to track the user activities on a website. Based on these evaluations, it is, for example possible, that advertisements tailored to the user are shown or that the popularity of entries is measured on the basis of statistics and that the website is optimised accordingly. For this purpose, personal information such as the location of the user, the status of a transaction (for example, business transaction on a purchasing platform) and statistics on the number of views can be logged and used via websites.

If external service providers are contracted to evaluate this user data, it must be taken into account that these service providers might correlate the user data with the data of other customers and web applications. On this basis, detailed user profiles can be created across other applications.

Possible techniques to collect user data are, for example, as follows:

• (persistent) cookies,
• web bugs (one-pixel picture elements, for example in an email for maintaining statistics on the number of views),
• browser fingerprints (for example using attributes such as installed utility programs, screen resolution, time zone, user agent, HTTP header),
• logging of the IP address.

In addition to this, the techniques can be combined to identify users in a more reliable manner.

If an evaluation of user data, especially personal data is planned or if a provider is to take over and carry out this service, the legal basis must be examined.