The concept of social connection is generally associated with the interactions, relationships, roles, and sense of connection that individuals, communities, or society may experience. Social connection has also become a specific term used in social science to represent the multiple ways that individuals connect to others emotionally, behaviorally, and physically. 

In his 2009 book, Loneliness: Human Nature and the Need for Social Connection, the late John Cacioppo, pioneer in loneliness research, defined social connection as something similar to the opposite of being thirsty or lack of pain: "'Not lonely' is also like not thirsty, not in pain. Health and well being for a member of our species requires being satisfied and secured in our bonds with other people, a condition of not being lonely that we call social connection."

Cacioppo and others spearheaded new research on the impact of loneliness on health in the last few decades, studying the impact of social isolation and loneliness. Loneliness is social pain, and the emotional region of the brain that is active when lonely is the same region that registers response to physical pain.

The term “social connection” has been proposed to encompass the different approaches to studying social relationships and their impact on life expectancy and quality of life. Cacioppo found that social connection helps regulate our physiological and emotional equilibrium. He wrote, "The social environment affects our neural and hormonal signals that govern our behavior and our behavior in turn creates changes in the social environment that affect our neural and hormonal processes. Social connection keeps our entire physical apparatus operating more smoothly."

Social scientists like Julianne Holt-Lunstad now measure social connection in three dimensions, the structure, function, and quality of our relationships with others. Structure is the number and variety of relationships, and the frequency of interactions. Function is the degree to which these relationships actually serve various needs, while quality is the degree of positivity of the relationships. Under structural, is someone married?, do they have a friends group?, etc. Under functional, what functions to these relationships really provide?, how much support or perception of support do they really have? What is the actual or perceived availability of the kinds of aid and resources that relationships provide? Under quality, are they really being included in their friends group? Are they married but it is an unhappy marriage?

The NIH relates the structural dimension to social isolation and the functional dimension to loneliness. Social isolation is objectively having few social relationships and social interactions, while loneliness is a subjective state, a perceived isolation or social deficit of experience from what is desired. Functional can be perceived as related to loneliness, since it is the subjective quality of one’s relationships. Cacioppo writes, “The solution to loneliness is not quantity but the quality of relationships. Human connections have to be meaningful and satisfying for each of the people involved, and not according to some external measure.” 

The U.S. Surgeon General’s Advisory on the Healing Effects of Social Connection and Community clarifies that social connection is a continuum, a gradient, and also dynamic, changing throughout our lives depending on life events. Further, just because someone does not report loneliness or isolation, this does not mean they have “high levels of social connection.” For example, one who is in a large involved family vs one who only has connection with coworkers at work. While individuals may not report a social deficit, or feel lonely, one may be missing out on high quality close relationships. 

Similar to the term social connection, the CDC discusses “social connectedness,” defining it as “the degree to which people have and perceive a desired number, quality, and diversity of relationships that create a sense of belonging, and being cared for, valued, and supported.” This echoes the structural, functional, and quality aspects discussed above. Further, they draw attention to having meaningful and regular, social exchanges, the sense of belonging and support from friends, family and others in the community, having closed bonds with others, and feeling loved, cared for, valued, and appreciated. 

John Cacioppo talked about the need for relational, collective, personal connection. Intimated connectedness, relational connectedness, and collective connectedness. "We need a circle of friends and family, be affirmed up close and personal, and have a need to belong in collectives, whether university, union, or club."  Similarly, Holt-Lunstad talks writes that the best solution to loneliness is across multiple dimensions the individual, the family and close relationships, the community, and the society.