What are Azure App registrations

 Azure App Registrations (formerly known as Azure Active Directory (Azure AD) App Registrations) are a way to configure and define applications that integrate with Azure AD for authentication and authorization purposes. They represent an entry point for an application to interact with Azure AD and other Microsoft services securely.

Here are some key points about Azure App Registrations:

1. Authentication and Authorization: Azure App Registrations define how an application authenticates with Azure AD and how it's authorized to access resources. This can include defining OAuth 2.0 and OpenID Connect protocols, specifying permissions (scopes) the application needs, and configuring authentication methods such as client secrets, certificates, or client credentials.

2. Single Sign-On (SSO): App Registrations can enable Single Sign-On (SSO) for applications, allowing users to sign in once and access multiple applications without needing to re-enter their credentials. This is achieved through protocols like OAuth 2.0 and OpenID Connect.

3. Service Principals: When an application is registered, it creates a service principal in Azure AD. The service principal represents the application's identity and credentials in the directory. It's used to authenticate and authorize the application when accessing Azure resources.

4. API Permissions: App Registrations define the permissions (scopes) that an application needs to access Azure AD or other Microsoft APIs. These permissions can be delegated (user-consented) or application permissions (admin-consented) and are granted to the application's service principal.

5. Redirect URIs: App Registrations specify the URLs where Azure AD should redirect users after they sign in or grant consent to the application. This helps Azure AD verify the authenticity of the request and return tokens or authorization codes to the correct endpoint.

6. Application Manifest: The application manifest for an App Registration provides a JSON representation of the application's configuration. It includes settings such as the application ID, display name, supported account types, and optional features like group membership claims.

7. Lifecycle Management: Azure App Registrations allow for lifecycle management of applications, including creating, updating, deleting, and disabling registrations as needed. This ensures that only authorized applications are allowed to access resources and that configurations are kept up to date.

8. Integration with Azure Services: App Registrations can be used to integrate applications with various Azure services such as Azure Functions, Azure Logic Apps, Azure Storage, and Azure Key Vault. This enables secure access to resources and data stored in Azure.

In summary, Azure App Registrations are a fundamental component for enabling secure authentication and authorization for applications in Azure AD, providing a centralized way to manage and configure application identities, permissions, and integration with Azure services.