* Applications

	Android applications are written in Java programming language. The Android SDK compiles the code, 
	along with data and resources. The result is .apk file witch is used by Android devices to install the 

* Operating system

	The Android operationg system is a multi-user Linux system in which each application is a different 

* Virtual machine

	Each application runs his own Linux process. Each process has its own virtual machine (VM) so an 
	application runs in isolation from other applications.

* Activities

	An activity represent a single screen with a user interface.

* Services

	A service is a compoment that runs in the background (without blocking user interaction with an 

* Content providers

	You can store data in the file system, an SQLite database, on the web.

* Manifest file

	The primary task of the manifest file is to inform the system about the application's components.