Service Principal

o delegate Identity and Access Management functions to Azure AD, an application must be registered with an Azure AD tenant. When you register your application with Azure AD, you're creating an identity configuration for your application that allows it to integrate with Azure AD. When you register an app in the Azure portal, you choose whether it's a single tenant (only accessible in your tenant) or multi-tenant (accessible in other tenants) and can optionally set a redirect URI (where the access token is sent to). For step-by-step instructions on registering an app, see the app registration quickstart