appIDs

AppID, or application identifier, is a stable, platform-assigned or developer-assigned string that uniquely identifies an application within a system. It is different from the app's name and is not usually user-facing except in developer tools.

In Apple's ecosystem, the App ID refers to a two-part identifier consisting of an App ID Prefix (often the Team ID) and a Bundle ID. Apps may use explicit App IDs or wildcard App IDs. The App ID is used to enable services and entitlements such as push notifications, iCloud, and Wallet, and is tied to provisioning profiles.

In Android, the applicationId is the unique identifier for an app on Google Play. It is defined in the Gradle build and is typically written in reverse-domain form, such as com.example.myapp. The applicationId is distinct from the Java package name and is the value that appears in the Play Console and on devices. Changing it after publication usually creates a new app.

For web or API-based apps, identifiers come in the form of OAuth 2.0 client IDs or OpenID Connect client IDs. These IDs identify the app to identity providers and cannot be treated as secrets. They are registered in the provider's console and used when exchanging tokens.

In enterprise or device-management environments, app IDs participate in app catalogs and management policies. Across ecosystems, app IDs are typically written in a reverse-domain style to minimize collisions.

Best practices include keeping IDs stable over time, using a unique namespace, avoiding user-facing elements in IDs, and not embedding sensitive data. They serve as identifiers for provisioning, signing, distribution, and API access rather than as security tokens.