Android is a Linux-based smartphone operating system and software platform created by Google.
The beta release of Android OS was released on 5 November 2007. The first SDK was released a week later, on 12 November 2007.
Android 1.0 was the first commercially available release of the OS. It was available on the pioneering device - the T-Mobile G1 (released October 2008 in the US and the UK) along with the Android source code.
Android 1.1 was pushed out on 9 February 2009, coinciding with the announcement of the HTC Dream, an internationally available twin of the T-Mobile G1.
Android 1.5 Cupcake was released on 30 April 2009. It was the first major Android overhaul and it also was the first Android release to be pet-named after a dessert - a tradition that has been kept alive ever since. Every subsequent Android release was named after a dessert, whose name started with the next letter of the alphabet.
Version 1.5 Cupcake introduced the software on-screen keyboard to Android and allowed the production of touch devices sans QWERTY keyboards such as the HTC Magic (announced February 2009). Equally importantly, it enabled Android smartphones to shoot video.
Along with that, v. 1.5 Cupcake added support for third-party software keyboards, third-party widgets, stereo Bluetooth, copy and paste in the web browser, screen auto-rotation, and an option to upload media to YouTube and Picasa.
Android 1.6 Donut was released on 15 September 2009. It added text-to-speech, updated Android Market now offered app screenshots, and it introduced support for WVGA screens. The camera became faster, and the gallery, camera and camcorder got deeply integrated with each other.
Android 2.0 Eclair SDK was released on 26 October 2009. Android 2.0 introduced multiple account sync, Microsoft Exchange email support, Bluetooth 2.1, the Quick Contact feature, showing a pop-up for call, SMS and email, as soon as you tap on a contact's avatar. The camera received new features such as flash support, digital zoom, scene mode, white balance, color effect and macro focus. The web browser UI was updated and some new features were added such as double-tap to zoom.
We saw the much overdue native support for multi-touch interaction with software. Live wallpapers were first introduced with Eclair, as well. The UI was redesigned, there were multiple performance improvements and we welcomed the support for more screen sizes and resolutions.
Google Maps Navigation was also introduced alongside Android 2.0 Eclair, quickly turning into a key selling point for Android smartphones in the supported countries.
Android 2.1 was a subsequent release, which was dubbed Eclair, too, as it wasn't a major update in terms of functionality. This sort of minor upgrades between major releases became commonplace in future versions.
Along with Android 2.1 Eclair Google introduced its first Nexus devices as well. Manufactured by HTC, but sold directly by Google, the Google Nexus One was released in January 2010 and in May 2010 it also became the first phone to be updated to Android 2.2 Froyo.
Android 2.2 Froyo also introduced push notifications, USB tethering and Wi-Fi hotspot functionality, an updated Android Market with automatic updates and batch install. The web browser could use embedded file upload fields. For the first time users could officially install applications to the external memory. The Adobe Flash support was another major new feature of the web browser.
Minor revisions were later released as updates such as Android 2.2.1, 2.2.2, and 2.2.3.
Android 2.3 Gingerbread SDK was released on 6 December 2010. This Android release offered an updated user interface and even better performance optimization.
It added native support for SIP VoIP internet telephony, improved text input and keyboard accuracy, enhanced copy/paste functionality (word-by-word selection), Near Field Communication (NFC) support, new audio effects such as headphone virtualization and bass boost, new system-wide download manager, and native support for a front-facing camera.
Developers also received a number of under-the-hood enhancements, giving them lower-level access to audio, graphics, and inputs, plus concurrent garbage collection for increased performance and native support for extra sensors such as gyroscopes and barometers. All this allowed devs to write faster native code.
Newer phones, which came out of the box with Gingerbread, now used the newer ext4 file system.
Android 2.3 Gingerbread however, was mainly touted for its enhanced power management, which took a more active approach to dealing with apps, which kept the phone going for much longer.
As of December 2012, Gingerbread is still the most widely used release of Android in the world.
Minor revisions were later released as updates such as Android 2.3.1, 2.3.2, 2.3.4, 2.3.5, 2.3.6, and 2.3.7.
Among the more important updates of those from a user's point of view is Android 2.3.4 Gingerbread (April 2011) introduced support for voice or video chat via Google Talk. Android 2.3.5 Gingerbread (July 2011) introduced an improved Gmail app, camera enhancements, and an even better battery efficiency.
Google continued the Nexus lineup with the launch of the Samsung-made Google Nexus S (December 2010), which was the first phone publicly released with Android 2.3 Gingerbread, and also the first phone to support NFC on both hardware and software level.
Android 3.0 Honeycomb SDK was released on 22 February 2011. It was Android's tablet-only version and was available concurrently with Android Gingerbread for phones.
Android Honeycomb introduced a new all-touch user interface, which did not rely on any physical navigation buttons. Unfortunately, it was plagued by performance issues throughout its product life.
Besides the visual differences, Honeycomb was first to introduce native hardware acceleration and support for multi-core processors. Honeycomb offered support for video calls over Google Talk even before Gingerbread smartphones did (the feature was only released in Android 2.3.4).
Later on Honeycomb was updated to Android 3.1 and 3.2 before Gingerbread and Honeycomb were both replaced by Android 4.0 Ice Cream Sandwich.
Android 3.1 added support for USB accessories such as external keyboards and pointing devices, joysticks and gamepads. Android 3.2 brought along refinements in performance via optimizations for a wider range of tablet devices.
Android 3.x Honeycomb release was not accompanied by a dedicated Nexus device, but Google widely used the Motorola XOOM as an ambassador and main demonstration platform for Honeycomb.
The Android 4.0.x Ice Cream Sandwich SDK was released on 19 October 2011.
Android ICS was released along with the Google Galaxy Nexus (November 2011) - the next successor in the popular Nexus lineup.
Android Ice Cream Sandwich or ICS, as it is better known, integrated the phone and tablet branches of Android into a single edition with a common interface, which again didn't rely on physical navigation buttons.
One of the most prominent changes in the UI was that the Widgets were now moved to a tab of their own in the main menu. Numerous other changes were introduced too, such as a new typeface throughout the UI - Roboto, the ability to launch apps from the lockscreen, support for real-time speech to text dictation, Face Unlock, Google Chrome web browser came preinstlalled with tabs and syncing of bookmarks, camera with time-lapse and panorama and a built-in photo editor, data usage analysis, and new calendar and mail apps. The UI graphics and animations got hardware acceleration and Wi-Fi Direct functionality was now supported natively.
Minor revisions were later released as updates such as Android 4.0.1 and 4.0.2.
In December 2011 Android 4.0.3 was released, fixing most bugs spotted in the previous releases plus adding enhanced video stabilization.
Android 4.0.4 is another minor update, which further enhanced the performance of the OS.
Further minor revisions were later released as updates ranging from Android 4.0.4 to 4.0.5 and 4.0.6.
Android 4.1 Jelly Bean SDK was released on 9 July 2012. A new version 4.2 was released later on under the same Jelly Bean moniker.
Android 4.1 Jelly Bean has a focus on performance, aiming to get rid of stutter by introducing Vsync (Vertical synchronization) of the timing of the frames output and the screen's refresh rate. Also, Jelly Bean adds triple buffering in graphics.
Instead of a smartphone, Google chose to display a tablet along with its Android 4.1 Jelly Bean release - the Google Nexus 7 (July 2012) was meant to show that Jelly Bean looked equally good on a tablet screen.
Beyond performance, there are other interesting features such as, offline voice recognition and dictation, expandable notifications, USB audio output and HDMI multichannel audio output, App encryption and Smart App updates. The Roboto font has also been refreshed, widgets are now dynamically resizable, and word prediction has been updated, too. Google Now is also a pretty big deal - it processes various data about your location, time of day, your schedule, etc. - and it shows you a pack of information cards, which it deems important to you in the current context. It also supports an advanced natural language voice search function, which is quite flexible.
Minor revisions of 4.1 Jelly bean were later released as updates such as Android 4.1.1 and 4.1.2.
Android 4.2 Jelly Bean builds on the foundations of 4.1 Jelly Bean and adds many new features. There is now support for multiple user accounts on tablets, native settings shortcuts in the notifications pane, gesture typing (ala Swype), wireless screen streaming via Wi-Fi Direct (over the Miracast protocol), widgets on the lockscreen, support for USB audio docks, redesigned camera app with HDR mode, Photo Sphere capturing and a built-in editor with filters, as well as further stability improvement.
A minor revision of Android 4.2 was later released as an update - Android 4.2.1. Most importantly it added native support for Bluetooth gamepads and joysticks.
The release of the Android 4.2 was supported with the announcement of a fourth Nexus smartphone - the LG-made Google Nexus 4 (November 2012).
Not only that, but Google also unveiled a 10-inch tablet - the Samsung-made Google Nexus 10.
Google announced Android Jelly Bean 4.3 in July 2013. Along with the announcement, Google also unveiled the 2nd generation Nexus 7 tablet, which was the first device to ship with Android 4.3 out of the box.
The improvements introduced by Android 4.3 are mostly marginal from a user's point of view:
Rumored to be called "Key Lime Pie", the next version of Android was announced on 3 September 2013 under the name KitKat (with the endorsement of Nestle).
A-GPS (Assisted GPS) | A2DP (Advanced Audio Distribution Profile) | AAC (Advanced Audio Coding) | Accelerometer | Airplane mode | Alarm Clock | Alphanumeric | AMOLED display (Active-matrix organic light-emitting diode) | Analog | Android | ANT+ | Antenna | APN (Access Point Name) | Apple iOS | aptX | Audio jack | Auto-focus | AVRCP (Audio/Video Remote Control Profile)
Calculator | Calendar | Call alerts | Calling Plan | Camera | Capacitive Touchscreen | Car Kit | Carrier | CDMA (Code-Division Multiple Access) | CDMA2000 | Cell | Chipset | cHTML (Compact HyperText Markup Language) | CIF (Common Intermediate Format) | Clamshell | CMOS (Complementary metal-oxidesemiconductor) | Color depth | Concatenated SMS | Corning Gorillla Glass | CPU (Central Processing Unit) | Crosstalk | CSTN (Color Super Twisted Nematic) | CTIA | Custom ringtones | CyanogenMod
D-Pad (Direction Pad) | DC-HSDPA (Dual Carrier or Dual Cell High-Speed Downlink Packet Access) | Digital Zoom | Display type | DLNA (Digital Living Network Alliance) | DNSe (Digital Natural Sound engine) | Downlink | DRM (Digital Rights Management) | Dual-band | Dual-Mode | Dual-SIM | DVB-H (Digital Video Broadcasting - Handheld) | Dynamic Memory
EDGE (Enhanced Data for Global Evolution) | EDR (Enhanced Data Rate) | EGPRS | EGSM (Extended GSM) | Email client | EMS (Enhanced Message Service) | EV-DO | EV-DV | Exchangeable covers | External Antenna Jack | External Display
FCC (Federal Communications Commission) | Feature Phone | Femtocell | Firefox OS | Firmware | Fixed-focus | Flash Memory | Flight mode | Flip-down phone | FM Radio | FM Transmitter | Form factor | FOTA (Firmware Over-The-Air) | FPS (Frames Per Second) | Frame Error Rate | Frequency | FTP (File Transfer Protocol)
H.263 | Half-QWERTY keyboard layout | Handwriting recognition | Haptics | Hot Spot | Hot Swap | HSCSD (High-Speed Circuit Switched Data) | HSDPA (High-Speed Downlink Packet Access) | HSDPA+ (High-Speed Downlink Packet Access Plus) | HSP (Headset Profile) | HSUPA (High-Speed Uplink Packet Access) | HTML (Hypertext Markup Language) | Hz (Hertz)
Land line | LCD (Liquid Crystal Display) | LED (Light-Emitting Diode) | Li-Ion (Lithium Ion) | Li-Polymer (Lithium Polymer) | LiMo OS | Linux | Location-Based Services (LBS) | Lock code | Long SMS | Long term evolution (LTE) | Loudspeaker
Macro | Maemo OS | mAh | Mass Storage mode | MB (Megabyte) | Mbps (Megabit per second) | MeeGo OS | Megapixel | Memory card slot | Memory effect | Messaging | MHz (Megahertz) | Micro USB | microSD | microSDHC | Microsoft Exchange (Server) | MIDI (Musical Instrument Digital Interface) | MIDP (Mobile Information Device Profile) | Mil-Spec (MIL-STD) | MIMO | Mini-USB | miniSD | MMC | MMCmobile | MMS (Multimedia Messaging Service) | Mobile games | Mobile High-Definition Link (MHL) | Mobile IM (Instant Messaging) | Mobile WiMAX | Mobility DisplayPort (MyDP) | Modem | Monochrome | MP3 (MPEG Layer 3) | MPEG (Motion Picture Experts Group) | MPEG-4 video | Multitouch input method | Music playback time (battery life) | Music Player
Packet Data | Pager | PC Sync | PCS (Personal Communications Service) | PDA (Personal Digital Assistant) | Phone Book Access (PBA) | Phonebook | PIM (Personal Information Manager/Management) | PIN code (Personal Identification Number) | Pixel | Pixel density (PPI) | Polyphonic ringtones | POP3 (Post Office Protocol) | Port | Predictive text input | PTT (Push-To-Talk) | PUK Code (PIN UnlocK Code) | Push
RAM (Random-Access Memory) | RBDS (Radio Broadcast Data System) | RDS (Radio Data System) | Resistive touchscreen | Resolution | Ringer ID | Ringing profiles | Ringtone | Roaming | ROM (Read-Only Memory) | RS-MMC (Reduced-Size Multi Media Card) | RSA (Rural Service Area) | RSS (Rich Site Summary) | Ruggedized (Rugged)
S60 user interface | SAP (SIM Access Profile) | SAR (Specific absorption rate) | Screen protection | SD (Secure Digital) | Secondary camera | Sensors | Side Keys | SIM | SIM lock | Single-Band | Skin | Slimport | Smartphone | SMIL | SMS (Short Messaging Service) | SNS (Social network service) | Soft keys | Soft Reset | Speed Dial | Stand-by time (battery life) | Stereo Speakers | Streaming Video | Stylus | Sub-QCIF | SVGA | Symbian | SyncML
Talk time (battery life) | TCP/IP | TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) | TEST | Tethering | Text messaging (texting) | TFD (Thin Film Diode) | TFT (Thin Film Transistor) | Theme | To-Do list | Touchscreen | Trackball | Transflash | Transflective | Tri-band