IN AN AGE OF MAJOR SCIENTIFIC advancements, the field of relationships may not be the first to jump to mind. But to overlook it would be a mistake. The past 30 years of research into this realm have deepened and changed our understanding of the very nature of human bonding.

Thousands of studies have linked the quality of people’s closest relationships to better health, longevity and well-being. People in happy, committed relationships live longer, enjoy better physical and psychological health, amass greater wealth and raise higher-performing children than people who are alone, in uncommitted relationships or in unhappy ones. Our close ties outside of romance, with friends, family and colleagues, offer similar benefits. It’s only natural: people are fundamentally social creatures, yearning for close, meaningful bonds with others. Our loyal relationships with friends, family and co-workers give our lives meaning.

The best news of all is that modern scientific findings—including our own at the Gottman Institute—have revealed not only how important lasting, satisfying relationships are but also how to achieve them, in love and in life. We’ve uncovered that the course of a partnership is determined by thousands of small moments: how two people deal with conflict, the way they create shared meaning, and the extent to which they develop trust and commitment. These, along with the many lessons illuminated in this TIME special edition, determine the true quality of relationships.