What is a tablet computer?

A tablet is a wireless, portable personal computer with a touchscreen interface. The tablet form factor is typically smaller than a notebook computer, but larger than a smartphone.

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The idea of tablet computing is generally credited to Alan Kay of Xerox, who sketched out the idea in 1971. The first widely sold tablet computer was Apple Computer’s Newton, which was not a commercial success. Technological advances in battery life, display resolution, handwriting recognition software, memory and wireless internet access have since made tablets a viable computing option.

Today, the most common type of tablet is the slate style, like Apple’s iPad, Microsoft’s Surface or Amazon’s Kindle Fire. External keyboards are available for most slate-style tablets, and some keyboards also function as docking stations for the devices.

Other styles of tablets include:

• Convertible tablets. These typically have a display that rotates 180 degrees and can be folded to close, screen up, over an integrated hardware keyboard. Convertible models may allow user input through a variety of methods in addition to the hardware keyboard, including natural handwriting with a stylus or digital pen and typing through a screen-based software keyboard.
• Hybrid tablets. Sometimes referred to as convertible or hybrid notebooks, a hybrid is like a regular notebook, but has a removable display that functions independently as a slate.
• Rugged tablets. A slate-like model that is designed to withstand rough handling and extreme conditions. Rugged tablets are usually encased in a thick protective shell and have shock-protected hard drives.

Tablet PC operating systems and features

Consumers and businesses have a range of tablet devices and operating systems from which to choose. Collectively, tablets have made numerous technological advances and gained increasing popularity in enterprise BYOD environments.

Microsoft’s Surface and Surface Pro tablet PCs are configured for a 64-bit Windows operating system. The Surface Pro 4 has a 12.3-inch screen and includes a stylus for drawing and writing on the touchscreen. Google’s Android is the best-selling tablet OS; the 6.0 Marshmallow version is featured on such devices as the Lenovo Pro 12 tablet, and 5.1 Lollipop is included in the Samsung’s Galaxy Tab E tablet PC.

Apple is largely responsible for igniting tablets’ current popularity, having released its first-generation iPad in April 2010. Since then, Apple has developed a family of associated devices, including the iPad Air, iPad Pro and iPad Mini. The iPad Pro is available in two touchscreen sizes: 9.7 inches and 12.9 inches. As for capacity, the iPad Mini ranges from 16 GB to 128 GB, while the iPad Pro is available with 32 GB to 128 GB of storage. Apple also released the Apple Pencil stylus for the iPad Pro.

Touch user interface

Samsung Galaxy Tab demonstrating multi-touchA key and common component among tablet computers is touch input. This allows the user to navigate easily and intuitively and type with a virtual keyboard on the screen. The first tablet to do this was the GRiDPad by GRiD Systems Corporation; the tablet featured both a stylus,a pen-like tool to aid with precision in a touchscreen device as well as an on-screen keyboard.

The event processing of the operating system must respond to touches rather than clicks of a keyboard or mouse, which allows integrated hand-eye operation, a natural part of the somatosensory system. Although the device implementation differs from more traditional PCs or laptops, tablets are disrupting the current vendor sales by weakening traditional laptop PC sales in favor of the current tablet computers. This is even more true of the “finger-driven multi-touch” interface of the more recent tablet computers, which often emulate the way actual objects behave.

Handwriting recognition

Chinese characters like this one meaning “person” can be written by handwriting recognition (人 animation, Mandarin: rén, Korean: in, Japanese: jin, nin; hito, Cantonese: jan4). The character has two strokes, the first shown here in dark, and the second in red. The black area represents the starting position of the writing instrument. Some tablet personal computers such as the Galaxy Note 10 utilize a stylus. These tablets often implement handwriting recognition. Tablet computers with finger driven screens usually do not. Finger driven screens are potentially better suited for inputting “variable-width stroke-based” characters, like Chinese/Japanese/Korean writing, due to their built-in capability of “pressure sensing”. However at the moment not much of this potential is already used, except in digital art applications like Autodesk Sketchbook for the iPad, and as a result even on tablet computers Chinese users often use a (virtual) keyboard for input.

Touchscreen hardware

Touchscreens are usually one of two forms;

• Resistive touchscreens are passive and can respond to any kind of pressure on the screen. They allow a high level of precision, useful in emulating a pointer as is common in tablet computers) but may require calibration to be accurate. Because of the high resolution of detection, a stylus or fingernail is often used for resistive screens. Limited possibilities exist for implementing multi-touch on a resistive touch-screen. As modern tablet computers tend to make heavy use of multi-touch, this technology has faded out on high-end devices where it has been replaced by capacitive touchscreens.
• Capacitive touchscreens tend to be less accurate, but more responsive than resistive screens. Because they require a conductive material, such as a fingertip, for input, they are not common among (stylus using) Tablet PCs but are more prominent on the smaller scale “tablet computer” devices for ease of use, which generally do not use a stylus, and need multi-touch capabilities.

Other touch technology used in tablets include:

• Palm recognition. It prevents inadvertent palms or other contacts from disrupting the pen’s input.
• Multi-touch capabilities, which can recognize multiple simultaneous finger touches, allowing for enhanced manipulation of on-screen objects.
• Some professional-grade Tablet PCs use pressure sensitive films that additionally allow pressure sensitivity such as those on graphics tablets.
• Concurrently capacitive touch-screens, which use fingertip detection can often detect the size of the touched area, and can make some conclusions to the pressure force used, for a similar result.

Form factors

Tablet computers are available in a variety of forms. To make comparison charts easier to read, we have divided all our reviewed tablet PCs into two main categories: slates and hybrids.

Slates

Slate tablet PCs got their name from writing slates, the bane of schoolchildren for centuries. Like those archaic pieces of rock, tablet PCs tend to be black and are used by touching the surface (with a piece of chalk in the former, with the heat from one’s own finger in the latter).

Slate tablets don’t come with a physical keyboard (though you can always buy them separately). Very rarely they come with a stylus (or ‘Apple Pencil’).

If you’re mainly interested in some brief Whatsapp chats, playing Angry Birds, surfing the net, watching movies and so on, then click through to the ‘slate’ section and use our tablet comparison charts to find one you like. If you need a keyboard to type longer emails, make notes in class, or run Office 365, read about hybrids.

Hybrids

Tablets are still a very new technology and new forms and uses are emerging all the time. There is a strong trend towards phablets and hybrid tablets. Mostly, when people talk about hybrids they mean tablets with a physical keyboard. Mostly.

Keyboards can be integrated into the tablet (via clever or crude mechanisms), or can be detachable.

Apart from with/without keyboard, we can further divide hybrids into the following categories:

• Detachables: The tablet and keyboard are two separate parts but are bought together and the software is optimized for a physical keyboard. Together they form a laptop-like portable computer, but rather underpowered compared to a laptop. The detachable keyboard serves as both input device and docking station, potentially extending battery life and offering juicy treats like full-size USB ports.
• Convertibles: With a convertible tablet, one half is a slate tablet and the other is a physical keyboard. The keyboard is integrated into the tablet and can’t be detached. The keyboard or display can slide, flip, rotate, or twist in order to convert from a laptop into a tablet.Generally speaking, they are more powerful than Detachables, and in some cases come close to the power of a laptop PC. Typically they run Windows as an Operating System.
• Laplets: The word laplet derives, obviously, from laptop and tablet. They are hybrids designed to run desktop applications. As processing power increases, we expect to see more of these available. For now, the trailblazer is the superb Microsoft Surface Pro series.

Other forms

Besides slates and hybrids, there are other, less common, tablets in the wild. Some date to the pre-iPad era.

Rugged tablets are one of these. They were used for data acquisition in challenging terrain. Rugged tablets have touchscreens and usually come with a stylus and integrated buttons for navigation and other dedicated tasks. There are models designed for use in cold mountainous regions, harsh desert climates, or even just to be manhandled by children in a classroom!

Booklets are another special form of tablet. These are dual screen tablets that can be folded like a book. They are as out of fashion as it is possible to get.

E-Readers started with the Amazon Kindle. They are primarily used for reading books, but since smartphones and tablets can be used for that task, the specialized e-reader market has declined. Still, they have their place.

Gaming Tablets represent a small but attractive niche that still attracts development money.