Brief summary for android

Android is a complete operating environment based upon the Linux® V2.6 kernel. Initially, the deployment target for Android was the mobile-phone arena, including smart phones and lower-cost flip-phone devices. However, Android's full range of computing services and rich functional support have the potential to extend beyond the mobile-phone market. Android can be useful for other platforms and applications.

Developing android application and it require tools which you need to install before developing any android application. 

If you're a new Android developer, we recommend you download the ADT Bundle to quickly start developing apps. It includes the essential Android SDK components and a version of the Eclipse IDE with built-in ADT (Android Developer Tools) to streamline your Android app development.

With a single download, the ADT Bundle includes everything you need to begin developing apps:

1. Eclipse + ADT plugin
2. Android SDK Tools
3. Android Platform-tools
4. The latest Android platform
5. The latest Android system image for the emulator

Download the ADT Bundle from: http://developer.android.com/sdk/index.html