Why might there be multiple manifest files in an application?

Multiple manifest files can appear in an application for the following reasons:

• Libraries and modules: Each library or module added to the project may have its own manifest file (AndroidManifest.xml). Gradle merges them with the main manifest during build.
• Flavors (Build variants): To create different versions of the app (e.g., free and paid), build flavors can be used. Each flavor can have its own manifest file in the src/<flavorName>/ folder. This manifest is merged with the main and library manifests.
• Build Types: Similarly, different build types (e.g., debug and release) can have their own manifests in the src/<buildType>/ folders.
• Tests: Test packages (e.g., androidTest) can also have their own manifest describing testing components.

During the build process, Gradle merges all these manifests into a single final AndroidManifest.xml file, which is packaged into the APK. Merge rules are used during this process, allowing elements to be added, replaced, or removed. Merge conflicts typically lead to build errors.