Exposure time is the length of time a message, alert, or prompt stays visible to a viewer. In cyber security, that duration matters because human attention is limited: if a warning disappears too quickly, users may miss a phishing cue, an MFA prompt, or a login error that should be checked before proceeding.
Security teams also think about exposure time when designing defenses. Longer visibility can improve recognition of suspicious messages and help users verify details, but it can also increase the chance of shoulder surfing or screen capture if sensitive information remains on screen. Attackers may exploit very short exposure time to hide malicious instructions, while defenders use timed warnings, lock screens, and clear on-screen notices to make important information available long enough to be noticed and acted on.