The Facebook SDK, from Meta, is a set of software development kits (SDKs), code libraries that an app includes in order to use a service, for connecting iOS and Android apps to Facebook. One of its main uses is Meta App Events: the app reports events, such as an install or a purchase, to Meta.
A developer adds the SDK to the app, through Swift Package Manager on iOS or Maven modules on Android, registers the app in Meta's App Dashboard, and puts the App ID and a client token into the app's configuration. The app then logs events, some automatically and others in code. The events appear in Meta's Events Manager and are used to measure app installs and ad results in Ads Manager. Other modules provide Facebook Login, sharing, Messenger, App Links and the Graph API. On iOS 14.5 and later, when a user has not given App Tracking Transparency (ATT) permission, Meta restricts the use of the data, with methods such as Aggregated Event Measurement.
The SDK code is published on GitHub as an open-source library under the Facebook Platform License.