Dark-web monitoring is a breach-alerting feature that searches leaked datasets, forums, and marketplaces for account-related data such as email addresses, usernames, passwords, or other identifiers. The goal is to tell a user when their information has surfaced in places that criminals use to trade stolen data.
In cyber security, this matters because exposed credentials are often reused in phishing, credential stuffing, and account takeover attempts. Monitoring does not stop a leak or remove the data, but it gives defenders early warning so they can change passwords, disable exposed aliases, reset recovery options, and review account activity. It is most useful as part of a larger defense that includes strong authentication, unique passwords, and phishing-resistant sign-in methods.