Cloud Access Security Broker (CASB) is a security solution that safeguards data and applications in cloud environments. It acts as a gatekeeper, monitoring and controlling access to cloud services, ensuring compliance with security policies, and detecting and preventing threats. CASBs provide visibility into user activities, enforce data encryption, and offer real-time threat protection. By acting as an intermediary between users and cloud services, CASBs enhance security in the cloud by addressing concerns related to data loss, unauthorized access, and compliance issues.