What system allows users to authenticate and gain access to various service providers by issuing a token?

The identity provider (IdP) is the system designed specifically to handle user authentication and issue tokens that allow users to gain access to various service providers. An IdP maintains user identities and credentials, validates them, and provides the necessary tokens for authentication purposes.

When a user attempts to access services from different providers, the IdP can authenticate them using single sign-on (SSO) functionality. This means that, after the user authenticates with the IdP, they receive a token that can be used to access multiple service providers without needing to log in separately for each one. This enhances user convenience by streamlining the authentication process across multiple platforms and applications.

In contrast, other options do not fulfill this specific role. Containers are primarily concerned with encapsulating applications and their dependencies. APIs serve as a means for applications to communicate with each other but do not inherently provide authentication services. SOAR encompasses security operations and incident management but does not specifically manage user identities or token issuance. Therefore, the identity provider clearly stands out as the correct answer for this question.