A trust boundary is a point within a computer system or network where data or commands transition from one level of trust to another, such as from a trusted internal network to an untrusted external network. Crossing this boundary typically requires additional security controls, like authentication, validation, or encryption, to prevent unauthorized access or manipulation. Identifying trust boundaries is crucial in cybersecurity, as it helps organizations determine where to implement safeguards to protect sensitive information and prevent security breaches. Proper management of trust boundaries reduces the risk of attacks that exploit differences in trust levels between system components.