Android - "King of applications"

Android is a software stack for mobile devices that includes an operating system, middleware and key applications. The Android SDK provides the tools and APIs necessary to begin developing applications on the Android platform using the Java programming language.

Features

• Application framework enabling reuse and replacement of components
• Dalvik virtual machine optimized for mobile devices
• Integrated browser based on the open source webkit engine
• Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0 specification (hardware acceleration optional)
• SQLite for structured data storage
• Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF)
• GSM Telephony (hardware dependent)
• Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
• Camera, GPS, compass, and accelerometer (hardware dependent)
• Rich development environment including a device emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE

Applications

Android will ship with a set of core applications including an 
Email client, SMS program, calendar, maps, browser, contacts, and others. 
All applications are written using the Java programming language.

ANDROID MARKET

Android Market is the online store developed by Google for Android devices. An application program called "Market" is installed in advance on most Android devices and allows users to browse and download apps published by third-party developers, hosted on Android Market. As of December 2010 there were about 200,000 games, applications and widgets available on the Android Market^.In April 2011 Google said there had been more than 3 billion Android apps installed and at end of June 2011 there are 6 billion apps installs from the Android market. The operating system itself is installed on 130 million total devices.