iPad is a line of tablets designed and marketed by Apple Inc. The first generation was announced on January 27, 2010 , while the second generation appeared on March 2, 2011 . It falls into a category between a smart phone and a laptop, they weight between 680 and 730 grams, and focus more on access than on creating applications and themes. Let's begin the tour and discover all the IPads that the market has to offer, Apple sold 3 million iPads within 80 days of its release.The iPad mini model, derived from the original iPad, and takes over the general functionality of the iPad in a more compact format. Its screen initially measures 7.9 inches, compared to 9.7' for the large model sold in parallel. In its first version, it inherited much of the hardware features of the iPad 2. The iPad mini 2 added the Retina display to the screen and so an excellent resolution that competes with the iPad Air, a better A7 processor and also improved Wi-Fi and LTE. Logically, that pixel density jump manifests on its value, particularly when reading a text became so much more enjoyable. The iPad mini 3 was a hit for its biometric sensor Touch ID, that allows to unlock the device simply by tapping the start button, and thanks to iOS 8.1, it enabled Apple Pay. The Apple iPad mini 3 screen is 7.9 inches in size and has a resolution of 2048x1536 and the pixel density is 324 dpi (measured in dots per inch) an IPS screen that protects from scratches and blows, a Oleophobic coating is also part of the combo. The golden case was a novelty for the device and it weighs 331 g and is 7.50 mm thick, while it is 134.70 mm high and 200.00 mm wide.The iPad mini 4 is Apple's smallest tablet. The iPad Mini 4 screen is 7.9 inches in size and has a resolution of 2048x1536. It measures 134.80 mm wide, 203.20 mm high, 6.10 mm thick and weighs only 298 g. In the memory section, it offers 1 GB of RAM, and 16 GB, 64 GB or 128 GB of internal memory or storage. In addition, the iPad Mini 4 has a main camera with an 8.0 MP resolution and it is capable of recording Full HD 1080p videos. The device basically has all the loved features of the IPad, updated, in a smaller size.The IPad pro has many performance improvements, supported by software updates. Plus, by combining software advances with Apple's most powerful A9X chip engine, it became a reference for efficiency in a machine. The iPad Pro comes with the option to download the Microsoft Office suite which includes PowerPoint, Excel, Word and OneNote applications as well as several free Adobe apps. The iPad Pro is the wide-format version of the iPad with its 2.9-inch Retina screen. The model features four speakers and the most powerful in-house processor ever developed by Cupertino. It is compatible with the Apple Pencil, and its sensitive layer brings the touch experience to a whole different level. The iPad Air model represents the 5th generation of the iPad and offers similar features to its siblings. The iPad Air is thinner and lighter by definition, however, keeps its power thanks to its potent chip and processor. The latest model of the line, the iPad Air 2 has extra add-ons, such as the presence of the Touch ID fingerprint reader, a new processor A8X, improved cameras and the traditional reductions of thickness and weight. The iPad Air 2 features the same anodized aluminum construction but is available in gold, spatial grey, and silver. The iPad Air 2 is more enjoyable to hold with one hand, the thinning creates a very balanced set of really comfortable handling, which can be held in the air for long periods of time without fatigue.The IPad market is particular, the adoption rate for this type of device is complex to understand because it does not have the same cycle as smartphones, but it doesn't resemble laptops at all. They do not need to be renewed as often as a telephone and they do not become obsolete in the same way as a computer.