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.

When it comes to why we unfriend, there are more possible explanations. Fifty-five percent of Facebook users call offensive comments cause for removing someone from their networks. The next most common reason is not knowing a friend well (41%) and sales soliciting (39%). The remaining explanations are a variety of social media etiquette SNAFUs.

Men are more likely to use Facebook for professional networking and dating. For women, Facebook is the place to connect with real life friends, snag deals and express creativity. Women are more likely to remove friends for offensive comments or a weak offline relationship.

The "State of Social Media Survey" polled 1,895 social media using adults (age 18 and older), recruited online between Mar. 31 and Apr. 14 through online forums, blogs and other social networking platforms.

Why do you friend and unfriend people on Facebook? Let us know your practices in the comments.