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Architecture of Android

To understand how Android works,take a look , which show the various layers that make up the Android operating system(OS).

The Android OS is a roughly divided into five sections in four main layers:

  • Linux kernel :- This is the kernel on which Android is based. This layer contains all the low-level device drivers for the various hardware components of an Android device.
  • Libraries :- These contain the code that provides the main features of an Android OS.For example , the SQLLite library provides database support so that an application can use it for data storage.The WebKit library provides functionalities for web browsing.
  • Android runtime :- The Android runtime is located in the same layer with the libraries and provides a set of code libraries that enable developers to write Android apps using the Java programming language.The Android runtime also includes the Dalvik virtual machine , which enables every Android application to run in its own process, with its own instance of the Dalvik Virtual machine.(Android applications are compiled into Dalvik executables).Dalvik is a specialized virtual machine designed specifically for Android and optimized for battery-powered moblie devices with limited memory and CPU power.
  • Application framework :- The application framework exposes the various capabilities of the Android OS to application developers so that they can make use of them in their applications.
  • Applications :- At this top layer are the application that ship with the Android device (such as Phone,Contacts , Browser and so on),as well as application that you download and install from the Android Market. Any application that you write and located at this layer.
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