Prior to the launch of the iPad in 2010, the tablet market barely existed, now it's awash with tablets, each offering different specifications from screen size to processing power. Before you flex your credit card, follow our guide to find out which tablet is best for you.

Tablets are an exciting style of computer and not surprisingly all the key hardware manufacturers want a slice of the pie. This inevitably means there are many tablets to choose from, and that they vary in terms of size, shape and features. Making your way through the maze might seem daunting, but if you break things down into key elements it becomes much easier to separate tablets from each other. So that's what we'll do here. We'll take a look at the central components of the tablet and explain how individual tablets might differ. You can use this information to help you decide on the priorities for your own tablet purchase, and that should help you hone in on the perfect tablet for you.

One area we aren't going to go into great detail here is the software platform on which tablets are built. That's not because this isn't important. Quite the opposite, in fact. It is so important that we've dedicated an entire article to that topic to look at the major operating systems in use today. See: Which tablet platform is best?

Leaving operating systems aside here means we can concentrate on other factors such as screen size, battery power, technical specifications such as processor and storage, camera capability, connectivity and expansion potential. Choosing the right mix for you will help you find the right computing companion.

Tablet buyers' guide: The Screen

As the point of interface between you and what any tablet offers, the screen is crucial. The most obvious area of variance between different tablets in these terms is the overall screen size and there is a lot of variety on offer. As with other computer screens, measurements are taken across opposite diagonal corners.

Sitting at the very top of the size tree are screens of around 10in. Apple's iPad offers a 9.7in screen, while even more screen area is delivered by the Samsung Galaxy Tab 10.1 – the name gives away the screen size. The ASUS Eee Pad Transformer and Motorola Xoom are among others that share this real estate.

Another whole class of tablets have smaller 7in screens such as the original Samsung Galaxy Tab, BlackBerry PlayBook, Dell Streak 7 and HTC Flyer. There are some tablets that sit outside these dimensions. LG's Optimus Pad, for example, has an 8.9in screen, and Samsung has a range of different-sized tablets that include 7.7in and 8.9in offerings as well as the 5in Galaxy Note. Meanwhile, Sony has the Tablet P, which features two 5.5in screens that fold up to make a clamshell device.

Actual size is only part of the screen factor. The iPad 2 with its 1024 x 768 pixels is different to the Samsung Galaxy Tab 10.1 and Asus Eee Pad Transformer with their 1280 x 800 pixels. The BlackBerry PlayBook and Samsung Galaxy Tab cram 1024 x 600 pixels into their 7in of screen area. If all this sounds complicated, rest easy. All the screen sizes and pixel resolutions quoted are perfectly good for everyday use. High-end tablets place a significant emphasis on good screens and it's only when you look at the budget end of the market that you might begin to see lower pixel resolutions, which could make for less satisfactory use, particularly for text or graphics intensive activities such as video viewing.

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

Tablet buyers' guide: Battery Power

Tablets are designed to be carried easily and are intended for use in all manner of situations, many – or even most – of which will be away from mains power. Good battery life is therefore vital. Yet while laptop computers almost always have removable batteries, tablets have a battery that you can't access. That means you can't buy a spare battery and keep it charged for when you need to use it.

What you'll actually get from a tablet depends a lot on your own pattern of use. Drawing down a lot of data over 3G can drain the battery power, for example. If you need a tablet that will last for a long time away from mains power, then check the quoted battery life, but understand that in real life you might not get the length of life suggested. It is also worth checking how your preferred tablet is charged – while smartphones are often charged by micro-USB connectors, that is not the case for every tablet. The iPad has a proprietary charge cable, as do some other tablets. You may need to carry a separate charge cable for your tablet of choice.

Tablet buyers' guide: Processor Power

Tablets can be asked to do an awful lot of work. Pop on and off the internet to send information to and fro. Plot your positions on maps and work out how to get you from one place to the next, giving directions as you go. Find and deliver video from the internet. Shoot video footage. Play games. Run processor intensive applications. And all the while manage background tasks such as keeping your email and social media feeds up to date. It is no wonder, really, that tablets need capable processors. The very top-end tablets run dual-core processors and in fact they are the de facto choice for both high-end tablets and high-end smartphones. Their benefit is that the tablet has access to two processing cores so that different tasks can be handled in parallel rather than having to be queued for the attention of a single processor. This has a knock on effect on the speed at which tasks can be achieved.

Tablet Buyers' guide: Storage Space

How much storage you think you might need on a tablet is rather dependent on what you end up using it for. But many people find that they use their tablet for a whole lot more than originally intended, so it might be an idea to think big in this regard. Some tablets come in versions with different amounts of internal storage. Think about choosing the highest capacity you can afford, but also take into account expansion options. Not all tablets accommodate microSD cards for expansion, but those that do give you the opportunity to add more storage memory as you need it, with 32GB cards retailing for around the £35 mark.

Tablet buyers' guide: Camera And Image Capabilities

Tablets come with either one or two cameras. A back-facing camera is ideal for taking photos, though using a tablet might be physically a bit unwieldy, particularly if it is one of the larger options. We've seen it done, though, and with 5 megapixels stills shooting cameras abundant on tablets they are in the same territory as smartphones, except with the advantage of a larger screen on which to display any stills or video footage captured.

Once you have a photo or video on your tablet there are plenty of options for doing useful and fun things. You can manipulate them on the device, share with others by email or social media, upload to sharing web sites such as Flickr or Picasa, or copy to your own computer for long-term storage.

One tablet even offers you the opportunity to shoot video and stills in 3D. The LG Optimus Pad has two cameras on its back for this purpose. You then view your 3D creations on the device using a pair of red/blue glasses or send them to a 3D TV via an HDMI cable.

When tablets come with a front-facing camera, you have another option – video calling. Skype is a popular enabler of video calling, and the login used on your main computer will work on your tablet too, so that all your contacts and settings are brought across. Skype is available for the iPad, and check the Android Market on your device or at to find out if your Android tablet of choice is supported.

See also: Tablets - a history

Tablet buyers' guide: Wireless Communications

Tablets can connect to the wider world via Bluetooth, WiFi and 3G. Many also have GPS built in, which means you can use them for location-based services such as mapping, and finding nearby attractions. Some tablets come in versions with or without 3G, with the former option being more expensive. If you opt for 3G then you have two choices: either buy a tablet outright and then add a 3G SIM of your choice, or you can buy a tablet from an operator complete with a mobile broadband plan. This latter option will be separate from any mobile phone contract you have. Typically you'll pay a price for the tablet that is less than the standalone asking price, and then a monthly tariff for data with variance in price depending on how much data you think you will use.

Tablet buyers' guide: On Device Connectivity

Tablets offer a range of different options for connecting to peripherals and external devices. All tablets should include headphones and microphone connectors and a wired connector for your computer via USB or, as in the iPad's case for example, a proprietary connector. The range on offer beyond that may vary. HDMI is a popular connector type, and this lets you send media footage to any other device that supports HDMI – typically this might be a TV. You may also find support for external mice and keyboards via USB on Android tablets too.

Tablet buyers' guide: Tablet Accessories

One of the most popular accessories for any tablet is an external keyboard. There are many keyboard docks for the iPad, including Apple's own. The Asus Eee Slate EP121, a tablet that runs Windows, comes with a Bluetooth keyboard, while the Asus Eee Pad Transformer goes one better and is an Android tablet that docks into a keyboard section so it looks like a traditional notebook. The keyboard section houses some additional connectors, too. Acer has a Windows-based tablet, the Iconia Tab W500, which also docks, laptop-like, into its own keyboard. In addition you can find a range of protective cases, screen protectors, docking ports, stands, speakers, and more. These help extend the kinds of uses to which you can put your tablet, so it is worth shopping around to see what's on offer for your chosen model. See page 94 for our guide to the best accessories.

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

Tablet buyers' guide: Software Expansion

All tablets come with a range of built-in software and you should be able to start being productive right out of the box. But one of the great plus points of tablets is the huge array of applications that can be downloaded from application stores that reside on the tablets themselves. Both the iPad and Android tablets benefit from vast application markets – though you should beware of the generalist mention of ‘thousands' of applications in each case.

For both the iPad and Android, the tablet-based software market is a development of the smartphone one. Applications were often designed for the smartphones first, and while they may be installed on tablets many don't fully exploit the bigger screen sizes. Be prepared for some applications to look smaller than you might like. That noted, there are plenty of applications designed to take full advantage of the tablet screen size.

So, there you have it – a background understanding of the key components of any tablet, and just some of the tablets that exploit these components. As we said at the outset, there is a lot of variety to be had.