Why should we be concerned? Scientists now link friendship to a remarkable range of benefits—both physical and mental: lower blood pressure, stronger immunity, reduced dementia risk, better sleep, and longer life.

As we navigate connections from infancy through childhood, adolescence, the various stages of adulthood and old age, we’ll meet today’s leading researchers blending insights from biology, sociology, neuroscience and psychology. We will also meet a diverse range of people whose personal stories illustrate what scientists are learning.

The exploration into the science behind human relationships can lead to a better understanding of friendship—the importance grows from a private affair to a matter of social responsibility and public health. Our connections with each other are opportunities to dramatically improve the health and security of our society, one friend at a time.