Federated identity is an authentication and identity management approach that allows users to access multiple systems, applications, or organizations using a single set of credentials. In a federated identity system, users authenticate once with their identity provider (IdP), such as Google, Microsoft, or Facebook, and then gain access to various resources without needing to log in again.

Federated identity is commonly implemented using standards like SAML (Security Assertion Markup Language), OAuth, or OpenID Connect, which enable secure sharing of authentication and identity information between different systems or domains. This approach enhances user experience by reducing password fatigue, minimizes security risks from managing multiple credentials, and simplifies identity management for administrators.

Federated identity is widely used in enterprise environments for single sign-on (SSO) solutions, as well as in cloud-based applications, allowing seamless access across platforms and organizations.