The iPad is a line of tablet computers designed and made by Apple, Inc. Tablet computers are portable computers with large displays that can be manipulated using touchscreen input. As of 2014, there are four iPad models on the market: iPad with Retina display, iPad mini, iPad mini with Retina display and iPad Air.
The iPad takes pictures, records and plays back video and audio, and connects to the Internet with its built-in Wi-Fi capability. Some models have Wi-Fi and cellular capability. All iPads have a slim form factor, making them easy to transport and use away from a desk. The iPad is powered by a rechargeable lithium-ion polymer battery that is sealed into the case, requiring a technician for replacement. The iPad uses flash memory for storage. All models can be ordered with different storage capacities, but the internal storage is not expandable.
The iPad’s operating system includes an on-screen keyboard, although an external keyboard can be used for more intense work. The functionality of the iPad is extended by the use of apps. Some of the basic applications that come installed on the iPad include a calendar, email client, web browser and notepad. Other apps and games can be downloaded through Apple’s App Store.