Today most people use social networks. The most popular of them, of course, is Facebook. But few know the principle on which the network selects a user for possible friends.
The most common is the view that Facebook puts in a list of recommendations through common friends. But this scheme is actually more complex.
In addition to the profile that the user creates in the social network, there is another. It contains a variety of information from your smartphone. For example, incoming messages or e-mail address.
When you check Facebook requests to open access to the phone book. In this way, the network is looking for people who are in any way associated with a user.
To protect yourself from the spread of information, is to prevent other users from finding your profile using the phone number or e-mail. This is done through the “Settings”section.