iOS

iOS from Apple Inc. (closed source, proprietary, on top of open source Darwin core OS)

The Apple iPhone, iPod Touch, iPad, and second-generation Apple TV all use an operating system called iOS, which is derived from Mac OS X. Native third party applications were not officially supported until the release of iOS 2.0 on July 11th 2008. Before this, "jailbreaking" allowed third party applications to be installed, and this method is still available. Currently all iOS devices are developed by Apple and manufactured by Foxconn or another of Apple's partners.

Windows

Windows Phone from Microsoft (closed source, proprietary)

On February 15th, 2010, Microsoft unveiled its next-generation mobile OS, Windows Phone. The new mobile OS includes a completely new over-hauled UI inspired by Microsoft's "Metro Design Language". It includes full integration of Microsoft services such as Windows Live, Zune, Xbox Live and Bing, but also integrates with many other non-Microsoft services such as Facebook and Google accounts. The new software platform has received some positive reception from the technology press.

Android

Android from Google Inc. (free and open source)

The Galaxy Nexus running Android 4.0.1

Android was developed by a small startup company that was purchased by Google Inc. in 2005, and Google continues to update the software. Android is a Linux-derived OS backed by Google, along with major hardware and software developers (such as Intel, HTC, ARM, Samsung, Motorola and eBay, to name a few), that form the Open Handset Alliance. Released on November 5th 2007, the OS received praise from a number of developers upon its introduction. Android releases prior to 2.0 (1.0, 1.5, 1.6) were used exclusively on mobile phones. Most Android phones, and some Android tablets, now use a 2.x release. Android 3.0 was a tablet-oriented release and does not officially run on mobile phones. The current Android version is 4.1. Android releases are nicknamed after sweets or dessert items like Cupcake (1.5), Frozen Yogurt (2.2), Honeycomb (3.0), Ice Cream Sandwich (4.0) and Jelly Bean (4.1). Most major mobile service providers carry an Android device. Since the HTC Dream was introduced, there has been an explosion in the number of devices that carry Android OS. From Q2 of 2009 to the second quarter of 2010, Android's worldwide market share rose 850% from 1.8% to 17.2%. On 15 November 2011, Android reached 52.5% of the global smartphone market share

About Smartphone

Origin of the term

Although devices combining telephony and computing were conceptualized as early as 1973 and were offered for sale beginning in 1994, the term "smartphone" did not appear until 1997, when Ericsson described its GS 88 "Penelope" concept as a "Smart Phone".
The distinction between smartphones and feature phones can be vague, and there is no official definition for what constitutes the difference between them. One of the most significant differences is that the advanced application programming interfaces (APIs) on smartphones for running third-party applications can allow those applications to have better integration with the phone's OS and hardware than is typical with feature phones. In comparison, feature phones more commonly run on proprietary firmware, with third-party software support through platforms such as Java ME or BREW. An additional complication in distinguishing between smartphones and feature phones is that over time the capabilities of new models of feature phones can increase to exceed those of phones that had been promoted as smartphones in the past.
Some manufacturers use the term "superphone" for their high end phones with unusually large screens and other expensive features. Other commentators prefer "phablet" in recognition of their convergence with low-end tablet computers.

Early years

IBM Simon and charging base (introduced August 16, 1994)

In 1973, Theodore George “Ted” Paraskevakos patented the concepts of combining intelligence, data processing and visual display screens with telephones, outlining the now commonplace activities of banking and paying utility bills via telephone.
The first cellular phone to incorporate PDA features was an IBM prototype developed in 1992 and demonstrated that year at the COMDEX computer industry trade show. A refined version of the product was marketed to consumers on 16 August 1994 by BellSouth under the name Simon Personal Communicator. The Simon was the first device that can be properly referred to as a "smartphone", even though that term was not yet coined. In addition to its ability to make and receive cellular phone calls, Simon was also able to send and receive facsimiles, e-mails and pages through its touch screen display. Simon included many applications including an address book, calendar, appointment scheduler, calculator, world time clock, games, electronic note pad, handwritten annotations and standard and predictive touchscreen keyboards.
In 1996, Nokia released the Nokia 9000, part of the Nokia Communicator line which became their best-selling phone of that time. It was a palmtop computer-style phone combined with a PDA from HP. In early prototypes, the two devices were fixed together via a hinge in what came to be described as a clamshell design. When opened, the display of 640×200 pixels was on the inside top surface and with a physical QWERTY keyboard on the bottom. Email and text-based web browsing was provided via their GEOS V3.0 operating system.
In the late 1990s though, the vast majority of mobile phones had only basic phone features so many people also carried a separate dedicated PDA device, running early versions of operating systems such as Palm OS, BlackBerry OS or Windows CE/Pocket PC. These operating systems would later evolve into mobile operating systems and power some of the high-end smartphones.
In early 2001, Palm, Inc. introduced the Kyocera 6035, the first smartphone in the United States. This device combined the a PDA with a mobile phone and operated on the Verizon Wireless network. It also supported limited web browsing. The device was not adopted widely outside North America.

HP iPaq h6315 (introduced July 2004)

In 2004, HP released the iPaq h6315, a device that combined their previous PDA, the HP 2215 with cellular capability.