ANDROID PROGRAMMING

What is Android?

1.1. Android Operation System 

Android is an operating system based on Linux with a Java programming interface.

The Android Software Development Kit (Android SDK) provides all necessary tools to develop Android
applications. This includes a compiler, debugger and a device emulator, as well as its own virtual machine to
run Android programs.
Android is currently primarily developed by Google. 
Android allows background processing, provides a rich user interface library, supports 2-D and 3-D graphics
using the OpenGL libraries, access to the file system and provides an embedded SQLite database.
Android applications consist of different components and can re-use components of other applications. This
leads to the concept of a task in Android; an application can re-use other Android components to archive a task.
For example you can trigger from your application another application which has itself registered with the
Android system to handle photos. In this other application you select a photo and return to your application to
use the selected photo.
1.2. Google Play (Android Market)
Google offers the Google Play service in which programmers can offer their Android application to Android
users. Google phones include the Google Play application which allows to install applications.
Google Play also offers an update service, e.g. if a programmer uploads a new version of his application to
Google Play, this service will notify existing users that an update is available and allow to install it.
Google Play used to be called Android Market.