What android actually is...?

• Android is a software stack for mobile devices 
• Interestingly, it is not yet another OS, but component based OS
• The Android SDK provides the tools and APIs necessary to begin developing applications on the Android platform using the Java programming language.
• Android is an operating system based on Linux with a Java programming interface.
• Android is an operating system for mobile devices such as smartphones and tablet computers.
• Android was developed by a small startup company that was purchased by Google Inc., and Google continues to update the software.