Alphabet compiles data about all of its users for a number of reasons. The company says it uses the data it collects to “maintain and improve [services and apps]develop new services, measure advertising effectiveness, protect against fraud and abuse, and personalize the content and ads you see on Google and our partners’ sites and apps.” This last part is also an easy selling point.If you’re selling a product that appeals to American women in their 20s and 30s with children, for example, then obviously all advertisements will be more successful if they specifically target that demographic than if they are simply shown to a random sample. Ad targeting means, to the extent of Google’s extensive capabilities, that most, if not all, of the ads you’ve paid for will be seen by someone who matches your target base.

So how does Google get this information? In fact, you voluntarily give a good part of it. If you filled out the form honestly when creating your Google account, the company will have your full name, gender, mobile number, and date of birth. It will also have access to your location each time you log in – or constantly if you’re using an Android device with location services enabled – as well as the type of content you watch and like on Youtube, the type of apps you you use, your credit card information and the websites you frequent. There are also things like the Google Opinion Rewards app, which offers Google Play Store credit in exchange for even more details about your life, including things as seemingly benign as the type of dessert you prefer.