A friend should be able to be an attentive listener, which made semiotician Roland Barthes wonder in his intriguing dictionary of love, "cannot friendship be defined as a space with total sonority?". This volume takes on the encyclopedic task - in the sense of Umberto Eco, where an encyclopedia is a very complex sign - to explore friendship in detail, not only as a form of love but in all its complexity as a bond that connects people and forms communities. Semiotics, the study of signs and meaning-making, is used alongside insights from a wide range of friendship studies to create a far-reaching intellectual resonance, or sonority, around friendship as a central human experience.

As a study of the significance of friendship, it presents findings from friendship research across the globe, enabling new ways of thinking about friends. It includes: