Inline prevention is a security control that sits in the live authentication path and can stop, delay, or challenge an access attempt before the login succeeds. Unlike pure detection tools, it does not only record suspicious behavior after the fact; it intervenes while the request is still in flight.
This matters in identity security because many attacks begin with stolen passwords, token abuse, or automated guessing against Active Directory, an IdP, or SaaS sign-in pages. If the control can enforce step-up authentication, block risky requests, or deny access from unusual sources, it can break the attack chain early. In practice, inline prevention appears in products that protect authentication flows, enforce MFA challenges, or apply risk-based policies at the point of access. It is especially useful when organizations need active enforcement rather than just alerts or later response.