What are Entra apps?
An Entra app is the identity a piece of software uses when it talks to Microsoft Entra.
A note on the name
Microsoft Entra ID was called Azure Active Directory (Azure AD) until Microsoft renamed it in 2023. The service is the same family of features; only the name changed. Many older articles and screens still say Azure AD.
The idea
Software cannot simply announce who it is. It needs to be registered, so that Entra can recognise it, give it an ID and decide what it may do. The things you can register include web apps, mobile apps, single-page apps, background services and scripts.
Two objects, one app
People often mix up two related things:
- App registration. The definition of the app, created in the tenant where it is developed. It holds details such as the application (client) ID, redirect addresses and credentials.
- Enterprise application (service principal). The instance of the app inside a particular tenant. It is where an organisation assigns users and controls how the app is used there.
A tenant is one organisation's dedicated space in Entra, identified by a tenant ID.
Apps that act for people, and apps that act alone
Some apps act on behalf of a signed-in user, such as a web app showing your calendar. Others run on their own with no user present, such as a nightly job. Entra handles both, and they use different kinds of permission, described on the next page.