iPhone is the smartphone range designed and distributed by Apple Inc. since 2007. The iPhone has its own Operating System, iOS, and its latest version is iOS7. More than 320 million iPhone are distributed over the world.
iPad is the famous tablet created and distributed by Apple Inc. since 2010. 121 million units have been distributed over the world by end 2012 and more than 375,000 applications are available in the AppStore. More and more corporate companies are using iPads in their daily work.
Android is the Google Operating System (OS) for smartphones and tablets. Many of the major handset manufacturers have chosen Android (Acer, HTC, Motorola, Sony, Samsung, LG, Panasonic, ...). In Q2 2013, Android accounts for more than 79% of the world mobile market share.
Firefox OS is a Linux-based open source operating system for smartphones and tablet computers being developed by Mozilla. Mozilla is targeting the users of basic phones in emerging markets that wish to possess a phone with access to the internet for a low price (a potential of 1 billion customers).
A mobile application is a software developed to be installed on a mobile device, such as a smartphone, a tablet, a PDA or any digital device. There are different Operating Systems and the most popular are: iOS (iPhone, iPad), Android (Google), Windows Phone (Microsoft), Blackberry OS (Blackberry), Firefox OS (Mozilla).
The most logic way to develop an application for a given platform is to write it in native code, what we could call the default language of the smartphone. But an alternative is hybrid applications, based on a set of languages common to all platforms. It implies a reduction of time (and cost) for both development and maintenance.