Quorum sensing is a cell-to-cell communication process that enables bacteria to modify their behavior collectively in response to changes in cell density and species composition. This process involves the production, release, detection, and group-wide response to extracellular signaling molecules called autoinducers. Recent studies have discovered new autoinducers in Gram-negative bacteria, revealed how these molecules are recognized by specific receptors, and identified novel regulatory components and network designs. This review examines how these features of quorum sensing signal-response systems combine to control collective behaviors in Gram-negative bacteria and discusses their implications for host-microbial associations and antibacterial therapy. The review highlights unusual signaling molecules, regulatory components, and heterogeneity in quorum sensing responses, emphasizing their roles in host-bacterial interactions.Quorum sensing is a cell-to-cell communication process that enables bacteria to modify their behavior collectively in response to changes in cell density and species composition. This process involves the production, release, detection, and group-wide response to extracellular signaling molecules called autoinducers. Recent studies have discovered new autoinducers in Gram-negative bacteria, revealed how these molecules are recognized by specific receptors, and identified novel regulatory components and network designs. This review examines how these features of quorum sensing signal-response systems combine to control collective behaviors in Gram-negative bacteria and discusses their implications for host-microbial associations and antibacterial therapy. The review highlights unusual signaling molecules, regulatory components, and heterogeneity in quorum sensing responses, emphasizing their roles in host-bacterial interactions.