The manifest file

Before the Android system can start an app component, the system must know that the component exists by reading the app's manifest file AndroidManifest.xml  Your app must declare all its components in this file, which must be at the root of the app project directory.

The manifest does a number of things in addition to declaring the app's components, such as the following:

• Identifies any user permissions the app requires, such as Internet access or read-access to the user's contacts.
• Declares the minimum API Level required by the app, based on which APIs the app uses.
• Declares hardware and software features used or required by the app, such as a camera, bluetooth services, or a multitouch screen.
• Declares API libraries the app needs to be linked against (other than the Android framework APIs), such as the Google Maps library.