Unless you've been living on Mars for the past 18 months, you will have noticed that the tablet market has exploded. Tablets have, however, been around for a lot longer than you'd think, and their viability was uncertain for a long time. Here's PC Advisor's history of the tablet PC.

Tablets are coming of age. It's been a long journey, longer than you might think, but you know a piece of technology has reached a key moment when your non-geeky friends start talking about it and, more importantly, owning and using it. That's what's happened to tablets, which in the past year have gone from a piece of kit generally used only by technophiles to something owned by people of all ages and with all levels of technical ability.

So, who currently uses tablets and what for? It's a question we almost don't need to ask any more. They are used by the young and the old, for business and leisure, in the home, on the train and in the office.

The tablet is established and, arguably, just like the PC, the laptop and the mobile phone before it, has the potential to change our lives. It didn't appear fully formed in the shape of the iPad in 2010, though. Tablets have a long history, and come from a long held desire to enjoy computing in the palm of every hand. They could be the future of portable computing, making notebooks unnecessary for many. Tablets are exciting both for what they are and what they could be. But how did we get here and where does the future hold?

Tablets: It's Got To Be Useful

Nobody is going to buy a new computing device that doesn't fit in with their lifestyle, no matter how clever it might be or now attractive it looks. Whether people come at tablets from a business or a leisure perspective, or a mix of both, the key overarching things that consumers want are: connectivity, great apps, instant startup, portability and ease of use.

The best tablets achieve all these things. They are influenced by lots of different strands of people's everyday lives, and while other technologies can also meet the demands, none can offer the wide variety of features that tablets manage to couple with ease of use. Smartphones come closest. Indeed they share many of a tablet's characteristics with tablets and they (and their predecessors) are a pivotal part of the evolution of tablets – of which more later...

Tablets: The Technology Requirements

While tablets have been around for longer than you think, and dream about for longer still, without the right technology they could never have become a reality. Several key technologies have come together to make tablets viable:

Processor power. Tablet processors need to be fast and power efficient. They must support complex apps carrying out complicated tasks. The more sophisticated software gets, the better processors need to be. The advent of low power dual?core processors played a pivotal part in the development of tablets, and means that they can handle all but the most processor-intensive tasks.

Battery life. Nobody wants a tablet that runs out of power after just a couple of hours. Decent battery life is crucial and a constant battle for tablet manufacturers as processors get faster and need more power, and tablet users want to perform more complex tasks, using software and hardware that requires lots of power. GPS, for example, is notorious for draining battery life, but people expect to use mapping and navigation services.

Component cost. Every component in a tablet from the screen to the chassis, the on/off button to the Wi-Fi chip, has a cost. This needs to be low enough that manufacturers can produce tablets at a price they can sell.

Part of this price is determined by how many units are produced – the higher this figure, the lower the cost of the components. However, it also requires the cost of raw materials and manufacturing to be affordable in themselves.

An ecosystem. A tablet's ecosystem comprises two elements – the operating system and apps. This goes hand in hand with slick hardware that looks great. Apple can take much of the credit for the giant leaps that have been taken in these areas. iOS has pushed others to refine their concept of a user-friendly OS; the App Store, which allows users to customise their iPads was pivotal in its early popularity and has been emulated elsewhere, most successfully by Google Android; and the overall design of Apple's tablet is masterful.
SIM support. A tablet that can't connect to the internet is of little use. The development of Wi-Fi, at home, in the office and in public places is crucial, but the ability to build SIM support into tablets has also been key to their success. The ubiquity of mobile phones means many people expect tablets to be able to connect in a similar way. Tablets that don't have a SIM option are hamstrung.

See also: Group test: what's the best tablet?

Tablets: How Did We Get Here?

The first Star Trek episode aired in 1966, and in the series the crew of the Starship Enterprise used handheld computers that can be argued as the fictional precursors of today's tablets. In 1968, American computer scientist Alan Kay came up with the Dynabook, a device with a screen and keyboard on a single flat plate. Targeted at children, it existed long before laptop computers came along.

It wasn't until 1989 though, that a tablet-like computer became commercially available in the shape of the GRiDPad computer. It had a black-and-white screen that was touch sensitive and it came with a stylus. This device was important not only in itself, but because one of the people who worked on it was Jeff Hawkins, who was pivotal in the development of PDAs (personal digital assistant). In 1992 he founded Palm Computing, and throughout the 1990s the company launched a series of PDAs, later introducing SIM support and morphing into smartphones.

Palm's history is complex, but a significant moment was when the hardware and software elements were split into separate companies. The latter developed WebOS and was bought by HP, which used the operating system in a couple of smartphones and an ill-fated tablet – the TouchPad, launched this year only to be discontinued with hardware sold off at rock bottom prices. Apple's Newton also deserves a mention. First launched in 1993, it was the company's first attempt at a tablet-style device. It had some features with which we are familiar today, including a touchscreen, though it didn't have wireless connectivity.

Another company that played a role was Psion, a company that today makes rugged handheld devices for harsh industrial conditions. Founded in 1980, it originally developed software for Sinclair Research's computers. In 1984, however, it launched the Psion Organiser, a handheld device. The company went on to release a number of portable computers including the Psion Series 3, a clam-shell PDA similar to an ultra-small laptop, with its own operating system; the even smaller Psion Siena; and the Series 7 in 1999. Psion's devices weren't tablets but they fed into the other strand of this history – PDAs and smartphones.
As Psion and Palm were pushing PDAs in the late 1990s, the vast majority of mobile phones had only basic phone features. It wasn't until the first decade of this century that manufacturers started combining cellular and PDA technology to create early smartphones. In 2001 Palm introduced the Kyocera 6035, a basic smartphone that was popular in the US. In the same year Microsoft rebranded its Windows CE Pocket PC operating system as ‘Microsoft Windows Powered Smartphone 2002'.

BlackBerry and, to a lesser extent, Palm popularised email on a portable device throughout the 2000s. But it wasn't until the launch of the iPhone in 2007 and the Android OS in 2008 that smartphones really broke through to become popular consumer devices, connected for web browsing and email, and offering full multimedia capabilities. Tablets would feed directly off this. Meanwhile, Microsoft was approaching tablets from a different angle...

NEXT PAGE: Microsoft and Tablets >>

See also: Which tablet platform is best?

The tablet market is growing exponentially, and tablets of various shapes and sizes proliferate on iOS and Google Android. But don't write off Microsoft. Not yet, anyway.

Microsoft and Tablets

Dominant in the desktop space, Microsoft's history with tablets is as long and torturous as its struggles in the mobile sphere. As far back as the early 1990s it introduced a product called Windows for Pen Computing (WPC). A software suite for Windows 3.1 that appended pen input to early Windows x86 tablet PCs. The tablets themselves used vanilla Windows as an OS. WPC let stylus-wielding execs utilise an on-screen keyboard, bark voice memos, or to make handwritten notes. There was even a primitive handwriting-recognition tool so that scrawled notes could be properly digitised (in principle, at least).

Microsoft encouraged software makers to utilise tablet capabilities in their products, and early Windows tablet PCs shipped with pen input capabilities already grafted on. The company improved on the first Windows for Pen when it released a second iteration for Windows 95, and made pen input intrinsic to all of its operating systems from XP forward. Indeed, when the company released XP in 2001, it took the opportunity to define what it thought the term ‘tablet' should mean. It said that Microsoft tablet PCs would be fully functional x86 PCs with pen, handwriting and voice recognition input. Note the lack of touch input, which came along only later.

Microsoft's hardware partners then produced tablet PCs that were little more than laptops with pen input. In time, the company released the dedicated Windows XP Tablet PC Edition. It tried another approach with its Smart Display back in 2002/3, though this was basically a monitor with no standalone functions. It also worked only when tethered to a PC by Wi-Fi or physical connection. Following the moderate success of Tablet PC, however, Microsoft moved things on when it started touting ultramobile PCs in 2006. This made Windows available on small and light touch-centric devices.

Microsoft had spent the decade between the birth of XP and the launch of the iPad evangelising tablets, with little or no impact outside of the enterprise, and vertical industries such as health and construction. And as we can see from the tabletisation of Windows 8, it hasn't given up yet. But unlike Apple, Microsoft is reliant on third parties to design and build its hardware, so while it was promoting tablet and ultramobile PCs, its partners started knocking up cheap netbooks to fulfil their clients' thin and light needs.

Indeed, whether it was coincidence, a spoiler or an unkind irony, a matter of weeks before Steve Jobs announced the iPad Microsoft's Steve Ballmer launched with great fanfare the latest iteration of Windows tablets: the Slate PC, made in conjunction with HP. The Windows-based HP Slate was something of a disaster: appearing after the iPad, only in the US, and making little impact.

Tablets no longer require a separate edition of Microsoft's operating system, and any version of Windows 7 offers handwriting recognition, multitouch input and the rest. Specialist Windows-based Tablet PCs continue to be produced, largely having their niche in business markets. But to be a truly successful tablet, the operating system needs to be built for touch, not merely touch enabled. Windows as it stands is a desktop operating system grafted on to tablet hardware, useful only to those who don't want to cut the Windows apron strings. After all, Apple didn't use OS X on the iPad. But therein lies the hope for Microsoft. What used to be ‘Mac OS X' is now simply ‘OS X', as Apple moves toward merging its desktop and mobile worlds. If Windows 8 is as successful as Microsoft hopes, it could be the first truly tablet?friendly Windows.

Tablets: Other Players

We can't, of course, talk about the evolution of tablet computing without mentioning the iPad. Despite Microsoft's long history trying to develop the platform, it was Apple's device that set the world of tablet computing on fire. By taking the already phenomenally successful iPhone and stretching it to tablet size, Apple turned Microsoft's ideas on their head. Less than 18 months after its launch, the iPad is the dominant player in the tablet market and the device that its competitors want to emulate; both in terms of design, but also sales.

Another major event in the development of tablet computing has been the release of Google's Android 3.x (Honeycomb) operating system. Designed specifically for tablets, it's used on a wide range of manufacturers' tablets. Some, notably HTC and Samsung, successfully put Android 2.x (Gingerbread) on to 7in tablets, while others did so less successfully, with hamstrung software markets being a major bone of contention among early adopters. It's only now, towards the end of 2011, that we are truly seeing a strong array of Android 3.x tablets.

Still, we like to have an eye on the future. Where do we go from here? The 3D ball has started rolling with LG's Optimus Pad, but that is a line which could be explored further. Sony's tablet P is dual screened fold-up tablet. Will that be popular? Will we see innovations like built-in projectors to send content to any blank wall nearby, super quality speakers, support for external games controllers? In five years time will the tablet have done what it threatens to do and killed the netbook market? Will there be households with no traditional computers at all, just tablets and useful peripherals like keyboards?

Matt Egan contributed to this feature