Originally developed by Andy Rubin and bought by Google in 2005, Android is the most widely used mobile operating system in the world, for smartphones and tablets. The open-source platform reached a new milestone in 2014, shipping over one billion devices and cementing its position as the number one operating system. According to market intelligence firm IDC, Android retained 81.5% of the global smartphone market in 2014, a supremacy that no other mobile operating system ever had before.

Android is credited with enabling the massive adoption of smartphones in both developed and emerging markets, as it allowed device makers to release low-end, cheap models, affordable for the average consumer. Unlike proprietary systems, like Apple's iOS for the iPhone and Microsoft's Windows Phone, Google licenses the operating system to device makers for free. The web search giant keeps control of the source code, based on the Linux kernel.

The app store for the OS, Google Play, is also the biggest in the market. It had 1,3 billion apps as of July 2014, against 1,2 billion on Apple's App Store, 300,000 on Microsoft's Windows Store, 240,000 on Amazon's Appstore and 130,000 on BlackBerry World.

The current version is Android 5.0, codenamed 'Lollipop' and released in November 2014 as a major revamp of the system. The original version was first made public in November 2007, two years after Google acquired the startup from founder Andy Rubin, who stayed in the company until October 2014. It was released ten months after Apple CEO Steve Jobs revealed the original iPhone and five months after the all-touchscreen device made its debut. In 2010, Android devices finally surpassed the iPhone. The Open Hanset Alliance, founded when Android was released, currently features 84 technology companies, which commit to openness in mobile phones.

Although it is free to license, the biggest device makers have to pay other fees to ship the OS in their smartphones, namely due to technology patents owned by companies like Microsoft and that are used on Android. The software has been centrefold in the so-called smartphone wars, as multiple patent infringement lawsuits and countersuits were filed in the last five years. Samsung, being the market leader in all counts, paid $1 billion in royalties to Microsoft during 2013. The two companies went into a full blown legal dispute over the fees agreement and ended up settling in the beginning of 2015.