What is the Difference Between LDAP and Single Sign-On?

LDAP (Lightweight Directory Access Protocol) and SSO (Single Sign-On) serve distinct but complementary roles in managing access to applications and services within organizations. LDAP functions as a structured, queryable directory service operating on a client-server model, organizing user information like authentication credentials and group memberships in a hierarchical manner called the Directory Information Tree (DIT). It is particularly suited for environments requiring centralized storage of user data and configuration settings, especially for legacy applications. On the other hand, SSO is an authentication mechanism that simplifies access by allowing users to log in once to gain entry to multiple independent software systems, enhancing user convenience and productivity through protocols like SAML, OAuth, and OpenID Connect. While LDAP is focused on managing directory information, SSO provides seamless access management, often involving federated identity management across different domains. Organizations may choose LDAP for centralized user management or SSO for simplified access, or both, to leverage LDAP's robust user data management with SSO's streamlined authentication processes. The choice depends on specific organizational needs and infrastructure, with an eye toward future innovations like passwordless authentication to further enhance security and user experience.