Mobile phones, like any electronic apparatus having two parts: the hardware (keyboard, screen, speaker ...) and software (display, read messages, calendar, games ...).
There is specialized software, the operating system that controls other applications, but mainly manages the hardware devices. In computers we can clearly distinguish the operating system (Windows, Linux, and Mac OS) from other programs.
In mobile phones, this was initially totally transparent to the user. The phone could make a very limited number of things that were already factory installed. Although the functions were more or less common, each mobile was different because it was handled with each manufacturer's own software, which could be very different from another.
Later we were allowed to install small mobile applications, especially games in Java. There we began to differentiate itself from the mobile software and we could install. Even as the mobile operating system still depended on the manufacturer, we should make sure that what we wanted to install would work in our terminal.
With the evolution of mobile devices and tablets, it became necessary to install and remove the more complex applications based on the needs of users and no sense having to create the application for each system manufacturer. It appeared that the real operating systems, operating in different mobile manufacturers.
The first mobile operating systems were Symbian (Panasonic, Siemens AG, Nokia, Sony-Ericsson and others), Palm (especially for PDAs), BlackBerry and Windows Mobile (Microsoft). Apple revolution the world of mobile phones with the launch of its iPhone family, with the operating system iPhone OS, and its multi-touch screen.
Android phone originally born in September 2008, then in February 2011 appeared Android application development 3.0 for tablets and in October 2011 appeared Android 4.0 that unified the two systems (phones and tablets) in one. The November 2012 version is Android 4.2.
The main advantage of using one of these operating systems is that we have a lot of applications. In addition, as with computers, two devices with the same operating system will be handled the same, but may have different screen, camera, one not integrated GPS, or are of a different manufacturer. Although there may be slight differences as each manufacturer may modify some aspects of Android.
The main difference between Android and other mobile operating systems is that it is free software based on Linux, and most of it is open source. This means that you will not pay anything for him, and that anyone can add enhancements. In proprietary systems, only the manufacturer can make modifications.
The main mobile application development company behind the development of Android is Google, who leads the Open Handset Alliance, a consortium of companies that are committed to follow open standards and free.
You can find more videos and information about the project on the official website of Android.