Definition
Single Sign-On (SSO) is a mechanism that allows a user to access multiple systems after a single Authentication event.
Human Explanation
The user signs in once and can then use multiple connected applications without entering login information again.
Why it Matters
SSO improves user convenience, reduces the number of passwords and supports centralised Identity management.
Conceptual Boundary
SSO does not replace Authentication. It is a way to reuse an already authenticated Identity across multiple systems.
Practical Perspective
A well-designed SSO system can improve convenience and security, particularly when combined with MFA.