Android OS is a Linux-based mobile operating system that primarily runs on smartphones and tablets.
The Android platform includes an operating system based on the Linux kernel, a GUI, a web browser and end-user applications that can be downloaded. Although the initial demonstrations of Android featured a generic QWERTY smartphone and a large VGA screen, the operating system was written to run on relatively inexpensive handsets with conventional numeric keypads.
The default UI of Android relies on direct manipulation inputs such as tapping, swiping and pinching to initiate actions. The device provides haptic feedback to the user via alerts such as vibrations to respond to actions.
When a user boots a device, Android OS displays the home screen, which is the primary navigation hub for Android devices and consists of widgets and app icons. Widgets are informational displays that automatically update content such as weather or news. The home screen display can differ based on the device manufacturer that is running the OS. Users can also choose different themes for the home screen via third-party apps on Google Play.
A status bar at the top of the home screen displays information about the device and its connectivity, such as the Wi-Fi network that the device is connected to or signal strength. Users can pull down the status bar with a swipe of a finger to view a notification screen.
Android OS also includes features to save battery usage. The OS suspends applications that aren't in use to conserve battery power and CPU usage. Android includes memory management features that automatically close inactive processes stored in its memory.
Android runs on both of the most widely deployed cellular standards and also supports:
Bluetooth
Edge
3G communication protocols, like EV-DO and HSDPA
Wi-Fi
Autocorrect
SMS and MMS messaging
Video/still digital cameras
GPS
Compasses
Accelerometers
Accelerated 3D graphics
Multitasking applications
