An acronym for Cloud Access Security Broker. This is a type of security that monitors and controls the cloud applications that an organization's employees might use. Typically, the control is enforced by routing web traffic through a forward- or reverse-proxy. CASBs are good for managing Shadow IT and limiting employee's use of certain SaaS or the activity within those SaaS but do not monitor third-party activity in the cloud–i.e. shared documents or email.