Application registration ensures that Microsoft Entra ID is aware of which applications exist, who can use them, and what resources they can access. Without registration, Microsoft Entra ID cannot issue tokens, enforce policies, or protect access to APIs and data.
From a security perspective, app registration establishes trust boundaries. Microsoft Entra ID only issues tokens to registered applications, and only for the permissions that have been explicitly approved. This prevents unauthorized apps from impersonating users or accessing organizational data.
Scenario
Imagine you are an application developer building a business application that stores sensitive company data. You need users to authenticate securely, and you want to restrict access based on identity and permissions. You also need the application to call Microsoft Graph to retrieve user profile information.
By registering the application in Microsoft Entra ID, you create an identity configuration that enables:
Secure authentication using Microsoft Entra ID.
Controlled authorization using scopes and roles.
Centralized enforcement of security policies such as Conditional Access.
Capabilities Enabled by App Registration
Registering an application enables several critical capabilities.
Custom branding allows you to control how your application appears on the Microsoft sign-in page. This is important because the sign-in experience is often the first interaction users have with your app, and consistent branding helps establish trust.
Tenant configuration lets you control who can sign in. You can restrict access to users in your organization only (single-tenant), or allow users from other tenants and even personal Microsoft accounts (multitenant).
Permission management allows the application to request specific permissions, such as user.read, which grants access to the signed-in user’s profile. You can also define custom scopes for APIs you expose.
Secure authentication enables you to configure how the application proves its identity. Confidential client apps can use client secrets, certificates, or managed identities to authenticate securely without user interaction.