Identity-First Security is an approach that makes identity the main control point for access, privilege, and security policy. Instead of trusting a device, network segment, or location by default, the system verifies who or what is requesting access and then applies policy based on that identity. This usually includes authentication, authorization, least-privilege access, and continuous review of trust.
It matters because many modern attacks start with stolen credentials, session hijacking, or abuse of overprivileged accounts. If identity is the gatekeeper, defenders can limit blast radius, enforce conditional access, and detect suspicious behavior from login patterns, privilege changes, and unusual resource requests. In real defenses, this appears in zero trust programs, identity governance, MFA, privileged access management, and telemetry-driven risk scoring. In practice, Identity-First Security turns account hygiene and access policy into frontline security controls rather than administrative tasks.