ms.subservice: external
ms.topic: overview
ms.date: 09/16/2025
ms.custom: it-pro, seo-july-2024
#Customer intent: As a dev, devops, or it admin, I want to learn about identity solutions for apps for consumers and business customers.
Learn more about [MFA in external tenants](concept-multifactor-authentication-customers.md) or see [how to enable multifactor authentication](how-to-multifactor-authentication-customers.md).
### Microsoft Entra reliability and scalability
Create highly customized sign-in experiences and manage customer accounts at a large scale. Ensure a good customer experience by taking advantage of Microsoft Entra performance, resiliency, business continuity, low-latency, and high throughput.
ms.subservice: external
ms.topic: overview
ms.date: 01/30/2026
ms.custom: it-pro, seo-july-2024
#Customer intent: As a dev, devops, or it admin, I want to learn about identity solutions for apps for consumers and business customers.
Learn more about [MFA in external tenants](concept-multifactor-authentication-customers.md) or see [how to enable multifactor authentication](how-to-multifactor-authentication-customers.md).
### Machine-to-machine authentication (M2M)
Machine-to-machine (M2M) authentication uses the [OAuth 2.0 client credentials flow](/entra/identity-platform/v2-oauth2-client-creds-grant-flow) to let an application authenticate directly with Microsoft Entra ID. This flow is intended for scenarios without user interaction, where backend services need to securely request access tokens and call APIs on their own behalf.
For Microsoft Entra External ID applications, you can configure M2M authentication by using the client credentials flow with either a client secret or a certificate. This approach allows your application to authenticate as itself when accessing APIs. To enable M2M authentication, you must use the [M2M Premium add‑on](https://www.microsoft.com/security/pricing/microsoft-entra-external-id/). Review your organization’s premium add‑on usage policy to understand cost implications and ensure compliance with internal governance and licensing requirements.
### Microsoft Entra reliability and scalability
Create highly customized sign-in experiences and manage customer accounts at a large scale. Ensure a good customer experience by taking advantage of Microsoft Entra performance, resiliency, business continuity, low-latency, and high throughput.