SAML (Security Assertion Markup Language), OAuth 2.0, and OpenID Connect (OIDC) serve as the foundational components for Ory Polis Single Sign-On (SSO) solutions, each addressing different aspects of identity management. SAML, developed for traditional web applications, enables federated authentication to an Identity Provider (IdP) but does not handle authorization, which became necessary with the rise of Single Page Apps and native platforms. OAuth 2.0 addresses this by allowing third-party applications to obtain limited access to user resources through an Authorization Code flow, providing a safer alternative to sharing user credentials. However, OAuth 2.0 has limitations in ensuring user authentication, which OpenID Connect resolves by introducing ID tokens that provide reliable proof of user identity. Ory Polis integrates these protocols to support SSO for various Identity Providers, such as SAML for Azure AD and OIDC for Google Workspace, by facilitating secure login processes. This involves setting up SSO connections, managing login flows, and acting as a proxy between client applications and IdPs, streamlining authentication and authorization processes while enabling scalability across multiple providers.