Android is an open source operating system for mobile phones and other devices with a generally small form factor which is managed by the Open Handset Alliance. Android utilizes the Linux kernel and a fully featured set of libraries and services.
The Android software stack can be summarized as follows:
The Linux kernel—where the software meets the hardware.
Hardware abstraction layer.
Core services such as process, memory, and file system.
Hardware-specific drivers such as Wi-Fi, Bluetooth, touchscreens, cameras, GPS receivers, and accelerometers.
Code libraries.
WebKit browser technology.
SQLite database.
Advanced graphics: 2D, 3D, SGL animation, OpenGL ES.
Packet Video’s OpenCore audio and video media support.
Services
Activities and views.
Telephony.
Windows.
Resources.
Location-based services.
Android run-time.
Core Java packages for a nearly full-featured Java programming environment (however, it is not quite a J2ME environment).
The Android platform, excluding the Linux kernel, is released under the Apache Software License (ASL).