What is the concept of attachment and why important?

Basis / relationship. Attachment is the 2 way emotional connection between (initially) a young child and his caregiver. When that first bond is healthy, it allows the child to bond with others in their world and develop reciprocity, the ability to take the perspective of another, and empathy. Without it, relationships with others usually are stormy, harmful, or non-existent for a lifetime. Treatment helps somewhat.