The Google APIs add-on is an extension to the Android SDK development environment that gives your Android applications easy access to Google services and data. The central feature of the add-on is the Maps external library, which lets you add powerful mapping capabilities to your Android application.
To use the add-on, install it in your Android SDK. From there, you can access the classes of the Maps library and compile your application against them. The add-on also includes a compatible Android system image that runs in the Android Emulator, which lets you debug, profile, and test your application before publishing it to users. When you are ready to publish your application, you can deploy it to any Android-powered device that runs a compatible version of the Android platform and that also includes the Maps external library.