A few key terminology and technology in Authentication and Authorization

SSO: A Single-Sign-On feature that enables users to sign in only once to access numerous applications within an organization after being authenticated using a single set of credentials. For instance, logging into mail.google.com will give you access to www.youtube.com.

Federated Authentication: SSO plus, the ability to authenticate across multiple organizations. For example, signing into Microsoft may grant you access to Salesforce, Atlassian, and other services. There are a number of different authentication protocols and standards, including OpenID Connect, OAuth, and SAML. Federated authentication standardizes the authentication communication cycle using one or more protocols.

OWIN: OWIN is a specification that enables decoupling web applications from web servers. It establishes a uniform method for using middleware in a pipeline to manage requests and related responses. Microsoft offers a version of OWIN called Katana that is provided as NuGet packages under the name Microsoft.Owin.* (https://github.com/aspnet/AspNetKatana).

ASP.NET Identity: Since the introduction of the ASP.NET membership system with ASP.NET 2.0 in 2005, there have been numerous modifications to how web applications typically handle authentication and authorization. When developing cutting-edge apps for online, mobile devices, or tablets, ASP.NET Identity offers a new perspective on what the membership system ought to be.

Duende IdentityServer: IdentityServer4 End-of-life (EOL) - What Next? Duende IdentityServer, The most adaptable and compatible OAuth 2.0 and OpenID Connect framework for ASP.NET Core. IdentityServer gives you full control over your UI, UX, business logic, and data.