An intimate relationship is a particularly close interpersonal relationship. It is a relationship in which the participants know or trust one another very well or are confidants of one another, or a relationship in which there is physical or emotional intimacy.

Intimate relationships play a central role in the overall human experience. Humans have a universal need to belong which is satisfied when intimate relationships are formed. Intimate relationships consist of the people that we are attracted to, whom we like and love, romantic and sexual relationships, and those who we marry and provide emotional and personal support. Intimate relationships provide people with a social network of people that provide strong emotional attachments and fulfill our universal needs of belongingness and the need to be cared for.

The systematic study of intimate relationships is a relatively new area of research within the field of social psychology that has emerged within the last few decades. Although the systematic study of intimate relationships is fairly recent, social thought and analysis of intimate relationships dates back to early Greek philosophers. Early scholarly studies were also interested in intimate relationships but were limited to dyads or small groups of people in the public and narrowly examined behaviours such as competing and cooperation, negotiation and bargaining and compliance and resistance.

Physical intimacy is characterized by romantic or passionate love and attachment, or sexual activity.