Every Android module has a namespace, which is used as the Kotlin or Java package name for its generated R and BuildConfig classes.
Your namespace is defined by the namespace property in your module’s build.gradle file, as shown in the following code snippet. The namespace is initially set to the package name you choose when you create your project.
android {
namespace "com.example.myapp"
...
}
While building your app into the final application package (APK), the Android build tools use the namespace as the namespace for your app’s generated R class, which is used to access your app resources. For example, in the preceding build file, the R class is created at com.example.myapp.R.
The name you set for the build.gradle file’s namespace property should always match your project’s base package name, where you keep your activities and other app code. You can have other sub-packages in your project, but those files must import the R class using the namespace from the namespace property.
For a simpler workflow, keep your namespace the same as your application ID, as they are by default.