John Bowlby formulated the attachment theory, the first attempt to define the complex emotional bonds that exist between humankind. It’s a relationship that involves an exchange of comfort, care and pleasure between the two parties. In addition, Bowlby believed that there were four defining characteristics needed to create and maintain attachment:

1.       Proximity Maintenance: the desire to be near the people we are attached to

2.       Safe Haven: Returing to the attachment figure for comfort and safety in the face of a fear or threat.

3.       Secure Base: The attachment figure acts as a base of security from where you can explore the surrouding enviroment. 

4.       Separation Distress:  Anxiet that occurs in the absence of the attachment figure.

EXO thought it sounded pretty simple.