All people possess a set of masks. And, all people use those mask. We wear several masks every day.
Masks exist to conceal.
We hide behind masks. By using our masks, we attempt to control how well other people know us. Typically, we allow a person to know us as well as we want him or her to know us. How well I allow you to know me depends on how secure I feel with you. So, a person has one mask for strangers, another for acquaintances, another for friends, another for best friends, and a special set of masks for family members.