What is an LDAP?

LDAP organizes entries in a tree structure (the Directory Information Tree) where each entry has a distinguished name and a set of attributes, and clients query it with a filter syntax to find, say, all users in a given department or group. It predates modern web-based identity standards by decades and remains the backbone of on-premises identity systems like Microsoft Active Directory, which many large enterprises still run alongside newer cloud identity providers. For SaaS vendors selling into enterprises, LDAP integration (often via a connector that bridges LDAP to SAML or OIDC) is frequently a hard requirement for sales to companies that haven't migrated their identity infrastructure to the cloud, even though the trend for new applications is toward directly supporting SSO protocols like SAML and OIDC instead of speaking LDAP natively. LDAP over an unencrypted connection is a real security exposure, so LDAPS (LDAP over TLS) or STARTTLS is expected in any serious deployment.