Product Manager, Eliza Crawford (2020) informs us that the reason data is collected on you across the Internet is to learn how you behave when you visit a website. This is to “gain insights about how … customers use” websites “to provide a personalised online experience, and to monetise the user by showing them targeted adverts.”
Explaining why online tracking occurs, Crawford (2020) says:
Pat Walshe (Privacy Matters) reminds us that behavioural data may include:
A study by Ghostery (2017) “revealed that trackers that collect data on internet users’ online behavior are present on at least 79 percent of websites (unique domains) globally. Web tracking has become so pervasive that approximately ten percent of websites send the data they’ve collected to ten or more different companies (unique tracker domains). In terms of web traffic, 15 percent of all page loads on the internet are monitored by ten or more trackers. According to the study, tracking scripts from Google (60.3 percent of page loads) and Facebook (27.1 percent) are the most prevalent”.