Single Sign-On (SSO) is a fundamental authentication mechanism that makes it easy to manage access by enabling users to sign in once and use many applications securely. It increases security by minimizing password-based threats, like phishing and weak passwords, while enhancing user experience by removing redundant logins. Organizations enjoy streamlined identity management, enhanced compliance, and reduced IT support expenses. But SSO can be a point of failure if not secured. To enhance protection, companies must implement Multi-Factor Authentication (MFA), implement zero-trust policies, and use real-time threat detection to protect user identities and avoid unauthorized access.