Gadget advice: Buying a tablet

In case you've been living in a cave (with no wi-fi) we're not talking about diamond-shaped blue tablets from dodgy internet sites, but the latest must-have gadgets for surfing the web on the go.

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The latest version of Apple's iPad has just been launched - but Apples are not the only fruit when it comes to tablet computers.

There are loads of rival devices, mostly using Google's Android operating system, which now offer similar or better performance - and differing functionality and compatibility.

We look at some of the key differentiating factors between the most-popular devices.

Operating system
Apple's iPad is still the market leader and thus so is iOS - Apple's operating system. This is one of its biggest selling points for many Apple fans, who love its user-friendly nature.

Many rival tablets run Android OS, the latest version of which at the time of writing was "Honeycomb" v3.2. This is powerful, flexible and designed specifically for tablets - but some feel it lags behind Apple's OS in terms of useability.

A few tablets run the Windows or Blackberry OS, but these are relatively rare.

How big do you want it?
Apple's original iPad had a screen that was 9.7in wide, and the subsequent versions have stayed the same size - but with better resolution.

Most Andorid tablets have 10.1in screens, although some are slightly smaller.

However, if you want something a bit more portable, there are a number of 7in screen devices running Android OS as well as the Blackberry Playbook tablet.

How will you connect to the net?
All tablets support wi-fi, but only some also have 3G coverage for connecting directly to the mobile broadband network.

How you intend to use your tablet will inform your decision on which you need - and of course 4G is just around the corner now, with a network expected to be up-and-running in the UK next year.

How appy are you?
Apps (or applications to give them their full name) are one of the biggest draws for many tablet buyers, yet others have no interest in them whatsoever.

Apple have the biggest selection of apps and a more rigorous screening process for them than Google operate for Android apps - but there are still thousands to choose from for Android devices and they are generally free or cheaper.

There are few apps for other operating systems.

What else can it do?
Does it have a video camera? How good is it? Does it have another front-facing one for video chats? These are all questions to ask yourself if you want to shoot a movie (some take high definition footage) or use Skype (or Chatroulette).

Some Android devices have detachable keyboards which can effectively turn them into laptops or netbooks, making them a much more flexible tool for occasional work use such as business trips.

Many tablets can connect to a TV set via a HDMI cable, allowing you to see streamed content on a bigger screen or replay your video footage for everyone to see.

Apple's iPad often requires expensive and unique leads to do things like this, while Android rivals are more likely to use industry standard solutions.

Other considerations
Storage space, screen resolution, reliability reports and processor speed are all additional factors that you might want to take into consideration, but it each case there is no "correct" spec to have. It depends on your requirements.

We hope we've given you a useful basic introduction to the key things to consider, but there's no substitute for doing your own research and there are a whole webful of sites out there with information on the subject.

What did we leave out? Comment below...