While some Internet interactions are online-only relationships, the most common reason we add friends on Facebook is because we know people in real life.

According to recent research from NM Incite, for 82% of Facebook users, knowing someone offline is reason to add them on the social network. The next most common reason for adding a friend is having many mutual friends, a practice reported by 60% of users.

The remaining reasons for adding friends include superficial aspects of your Facebook profile such as physical attractiveness and friend count — which is not surprising considering many users make their posts and comments visible to only their Friends. You can see the complete results of the study in the graphic below.