Data leak prevention (DLP) is a set of tools and practices that are used to prevent sensitive or confidential data from being disclosed to unauthorized individuals. DLP systems are designed to identify and prevent accidental or intentional data leakage from an organization, either through external channels such as email or through internal channels such as USB drives or file-sharing systems. 

Typically, DLP systems work by monitoring data as it is being transmitted or accessed and blocking any unauthorized attempts to access or transmit sensitive data. Additionally, they may include features such as data classification, which allows organizations to identify and label data based on its sensitivity, and data loss prevention policies, which outline the rules and procedures that must be followed to protect sensitive data.  

DLP is an important aspect of overall data security, and it can help organizations meet regulatory compliance requirements, protect their intellectual property, and reduce the risk of data breaches and other security incidents.