On the web there are a lot of data, that is increasing every day, so the search and navigation must be guided. In order to do that, web personalization has been developed.
Web personalization uses algorithms to process information collected about the user (digital traces) with or without his assent in order to provide more relevant results.
This system, by prioritizing and filtering some results, it affects our knowledge. Google, Facebook, Amazon, Yahoo! and many other companies use this system every day.