The study of bacterial sociality, understanding when and how bacteria interact and the consequences of those interactions, has rapidly grown in popularity over the last 20 years. This has revealed that bacteria engage in a remarkable variety of social interactions, including complex cell-cell communication, the exchange of an arsenal of inhibitory molecules, and the sharing of metabolites. These interactions can have significant consequences for the host or environment they reside in, and numerous mechanisms of interaction have attracted significant interest for their therapeutic potential. The present special issue contains eight review articles addressing three major questions in bacterial sociality (Who is where? How are they interacting? And what are the implications of this?) alongside five methods-focused articles that introduce some particularly valuable approaches for the study of bacterial interactions.