The iPad is a line of tablet computers designed, developed and marketed by Apple Inc. primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. Its size and weight falls between those of contemporary smart phones and laptop computers. The iPad runs the same operating system as the iPod Touch and iPhone —and can run its own applications as well as iPhone applications. Without modification, the iPad will only run programs approved by Apple and distributed via the Apple App Store (with the exception of programs that run inside the iPad's web browser).
Like iPhone and iPod Touch, the iPad is controlled by a multitouch display—a departure from most previous tablet computers, which used a pressure-triggered stylus—as well as a virtual onscreen keyboard in lieu of a physical keyboard. The iPad uses a wireless local area network ("Wi-Fi") connection to access local area networks and the Internet. Some models also have a 3G wireless network interface which can connect to HSPA or EV-DO data networks and on to the Internet. The device is managed and synced by iTunes running on a personal computer via USB cable.
Apple released the first iPad in April 2010, and sold 3 million of the devices in 80 days, During 2010, Apple sold 14.8 million iPads worldwide, representing 75 percent of tablet PC sales at the end of 2010.
By the release of the iPad 2 in March 2011, more than 15 million iPads had been sold – more than all other tablet PCs combined. In 2011, it is expected to take 83 percent of the tablet computing market share in the United States
Apple's first tablet computer was the Newton MessagePad 100, introduced in 1993, which led to the creation of the ARM6 processor core with Acorn Computers. Apple also developed a prototype PowerBook Duo-based tablet, the PenLite, but decided not to sell it in order to avoid hurting MessagePad sales. Apple released several more Newton-based PDAs; the final one, the Message Pad 2100, was discontinued in 1998.
Apple re-entered the mobile-computing markets in 2007 with the iPhone. Smaller than the iPad but featuring a camera and mobile phone, it pioneered the multi touch finger-sensitive touchscreen interface of Apple's iOS mobile operating system. By late 2009, the iPad's release had been rumored for several years. Such speculation mostly talked about "Apple's tablet"; specific names included iTablet and iSlate. The eventual name is reportedly a homage to the Star Trek PADD, a fictional device very similar in appearance to the iPad. The iPad was announced on January 27, 2010, by Steve Jobs at an Apple press conference at the Yerba Buena Center for the Arts in San Francisco.
Jobs later said that Apple began developing the iPad before the iPhone, but temporarily shelved the effort upon realizing that its ideas would work just as well in a mobile phone
Apple Inc. CEO Steve Jobs unveiled the iPad 2, the second generation of the device, at a March 2, 2011, press conference, despite being on medical leave at the time. About 33% thinner than its predecessor, the iPad 2 has a better processor, a dual core Apple A5 that Apple says is twice as fast as its predecessor for CPU operations and up to nine times as fast for GPU operations. It includes front and back cameras that support the FaceTime video calling application, as well as a three-axis gyroscope. It retains the original's 10-hour battery life and has a similar pricing scheme.
The iPad 2 has been available for purchase, depending on stock availability, since March 11, 2011, at Apple retail stores in the United States, as well as to United States customers shopping online at Apple's retail website. The iPad 2 was released internationally in 25 other countries on March 25, 2011, including Australia, Canada, France, Germany, Mexico and the United Kingdom, but not Japan as originally scheduled due to the earthquake and tsunami.
Screen and input
The iPad's touchscreen display is a 1024 × 768 pixel, 19.1×14.8 cm liquid crystal display (diagonal 9.7 in (24.6 cm)), with fingerprint- and scratch-resistant glass. Steve Jobs backed the choice of screen size, saying a 7-inch screen would be "too small to express the software" and that 10 inches was the minimum for a tablet screen. Like the iPhone, the iPad is designed to be controlled by bare fingers; normal, non-conductive gloves and styli do not work, although there are special gloves and capacitive styli designed for this use.
The display responds to other sensors: an ambient light sensor to adjust screen brightness and a 3-axis accelerometer to sense iPad orientation and switch between portrait and landscape modes. Unlike the iPhone and iPod Touch's built-in applications, which work in three orientations (portrait, landscape-left and landscape-right), the iPad's built-in applications support screen rotation in all four orientations, including upside-down. Consequently, the device has no intrinsic "native" orientation; only the relative position of the home button changes.
There are four physical switches on the iPad, including a home button near the display that returns the user to the main menu, and three plastic physical switches on the sides: wake/sleep and volume up/down, plus a software-controlled switch whose function has changed with software updates. Originally the switch locked the screen to its current orientation, but the iOS 4.2 changed it to a mute switch, with rotation lock now available in an onscreen menu.] In the iOS 4.3 update, released with the iPad 2, a setting was added to allow the user to specify whether the side switch was used for rotation lock or mute.
The original iPad had no camera; the iPad 2 has a front VGA camera and a rear-facing 720p camera, both capable of still images and 30fps video. The rear-facing camera has a 5x digital zoom for still images only. Both shoot photo and video in a 4:3 fullscreen aspect ratio, unlike the iPhone 4, which shoots in a16:9 widescreen aspect ratio. Unlike the iPhone, the iPad does not support tap to focus. The cameras allow FaceTime video messaging with iPhone 4, iPod Touch 4, and Snow Leopard Macs.
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