The Communicate Bond Belong (CBB) theory is an evolutionary and motivational explanation of human communication's role in the relational functions of social interaction. CBB theory conceives of all social interactions as energy expending, but posits that only some social interactions are striving behaviors (i.e., actions taken to satiate a need). CBB theory proposes that social interaction operates within a homeostatic system, developed from internal pressures to satiate a need to belong, shaped by competing desires to invest and conserve social energy, and adaptable to new social circumstances and technological affordances. The theory bridges gaps among evolutionary and social psychology theories and interpersonal communication theories by attending to the multifunctional nature of everyday talk in relation to fundamental human needs.