It is an operating system for mobile
Interestingly, it is not yet another OS, but component basedOS
It has an integrated Java Virtual Machine
System interfaces are exposed only through Java libraries
It is based on the Linux Kernel
An Android SDK is provided to let developers build applications on top of the OS but not extend the OS itself
The SDK includes
Android packages
sample files
Documentation
A Simulator
The offical site of Android broadly classfies the technical parts of the OS as
consisting of
Linux Kernel
Android Runtime
Libraries
Application...
