Quorum sensing is a bacterial communication process that allows cells to synchronize gene expression based on population density. This review focuses on the quorum-sensing systems of Vibrio harveyi and Vibrio cholerae, highlighting their differences from other bacterial systems. These systems use autoinducers, small molecules that trigger gene expression changes. V. harveyi and V. cholerae have distinct quorum-sensing architectures, with V. harveyi using multiple autoinducers (HAI-1, AI-2, CAI-1) and V. cholerae relying on a single autoinducer (CAI-1). Both systems involve signal transduction through two-component systems, with LuxO-P activating gene expression of small regulatory RNAs (Qrrs) that control quorum-sensing regulators like LuxR and HapR. The Qrrs in V. harveyi function additively, while in V. cholerae they function redundantly. The systems also involve feedback regulation, with LuxO-P and LuxR-Qrr loops controlling gene expression. The quorum-sensing networks in these bacteria allow them to adapt to different environments and lifestyles, with V. harveyi being a free-living marine bacterium and V. cholerae a pathogen that alternates between human hosts and aquatic environments. The study of these systems has revealed fundamental mechanisms of signal detection, transduction, and information processing in bacterial communication.Quorum sensing is a bacterial communication process that allows cells to synchronize gene expression based on population density. This review focuses on the quorum-sensing systems of Vibrio harveyi and Vibrio cholerae, highlighting their differences from other bacterial systems. These systems use autoinducers, small molecules that trigger gene expression changes. V. harveyi and V. cholerae have distinct quorum-sensing architectures, with V. harveyi using multiple autoinducers (HAI-1, AI-2, CAI-1) and V. cholerae relying on a single autoinducer (CAI-1). Both systems involve signal transduction through two-component systems, with LuxO-P activating gene expression of small regulatory RNAs (Qrrs) that control quorum-sensing regulators like LuxR and HapR. The Qrrs in V. harveyi function additively, while in V. cholerae they function redundantly. The systems also involve feedback regulation, with LuxO-P and LuxR-Qrr loops controlling gene expression. The quorum-sensing networks in these bacteria allow them to adapt to different environments and lifestyles, with V. harveyi being a free-living marine bacterium and V. cholerae a pathogen that alternates between human hosts and aquatic environments. The study of these systems has revealed fundamental mechanisms of signal detection, transduction, and information processing in bacterial communication.