A cloud access security broker is a control layer that gives organizations visibility and policy enforcement between users or systems and cloud services.
A cloud access security broker, usually called a CASB, is a control layer that gives organizations visibility and policy enforcement between users or systems and cloud services. In plain language, it helps security teams see and control how SaaS and other cloud services are being used.
CASB matters because cloud adoption often moves faster than centralized security review. Users may store sensitive data in approved tools, personal tenants, or lightly governed services without the organization having clear visibility into what is happening.
It also matters because cloud risk is not only about infrastructure settings. Data movement, user behavior, and SaaS access patterns all shape exposure.
CASB appears in SaaS governance, shadow-IT discovery, cloud access monitoring, policy enforcement, and incident investigation. Teams connect it to Identity Federation, Conditional Access, Data Classification, Audit Log, and Cloud Security Posture Management.
It is most useful when organizations need better visibility into data handling and cloud-service usage beyond traditional perimeter assumptions.
A company learns that employees are uploading documents to multiple cloud file-sharing services outside the standard approved platform. A CASB helps identify that behavior, flag sensitive uploads, and enforce policy around which services can be used.
A CASB is not the same as Cloud Security Posture Management. CSPM focuses more on configuration and posture within cloud environments, while CASB focuses more on visibility and control around cloud-service usage and data movement.
It is also not just a proxy for blocking traffic. The broader value is visibility, policy, and governance across cloud-service activity.