SignOn

SignOn is a term used in information technology to describe the act of authenticating a user to access a computer system, service, or application. In common usage, sign-on is synonymous with login, sign-in, or authentication, typically involving the entry of credentials such as a username and password, though modern implementations increasingly rely on biometrics, device-based verification, or multi-factor authentication.

In enterprise and web contexts, sign-on is often implemented as single sign-on (SSO), which allows a user to authenticate once to an identity provider and obtain access to multiple dependent applications without re-entering credentials. SSO relies on standards and protocols such as SAML, OAuth 2.0, OpenID Connect, and WS-Federation, enabling interoperability between identity providers (IdP) and service providers (SP). Implementations may be centralized on an on-premises directory or provided as cloud-based identity services.

Security considerations: sign-on systems reduce password fatigue but concentrate risk around the identity provider; protecting credentials, enforcing MFA, managing session lifetimes, and defending against phishing and token theft are critical.

Brand usage: SignOn is used as a brand or product name by several technology companies and software offerings, ranging from identity and access management tools to consumer apps. Because it is a common term and branding choice, there is no single official SignOn entity.

See also: authentication, login, sign-in, single sign-on, identity provider, multi-factor authentication.