In the embryonic days of computers, the world of software was dominated by callow youths in their bedrooms – or in Bill Gates' case, a garage – with some of the greatest names in software starting with little more than a book on coding and a lot of free time. Yet as software became big business, the bedroom developer all but disappeared. No longer could one person produce a commercially viable title – instead teams of programmers and marketers were needed.

Now, the bedroom developer is being given a new lease of life, and it's all down to Apple and the much-hyped iPhone. The gadget has been an astonishing success – the Californian company claims that since the phone's launch last year, Apple has already become the world's third-largest mobile phone supplier in terms of revenue.

However, it wasn't until last July that the true capabilities of the iPhone started to be revealed, and Apple launched the App Store, a simple-to-use online shop selling software that can transform your iPhone, or iPod touch, into a device with a thousand uses. When it first launched, around 500 applications (a mixture of paid and free) were available, but now there are nearly 6,000 – last month brought the total downloads to 200 million.

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The applications, almost all of which are made by 3rd-party developers, can turn your iPhone into a remote control for your laptop; a reference guide for making cocktails; a tool to measure the MPG of your car, and countless other features. Speaking during Apple's fourth-quarter earnings conference call in October, Steve Jobs, the company's co-founder and CEO said: "We've never seen anything like this in our careers... It is clear that customers are now attracted to iPhone not only for its amazing functionality and revolutionary multi-touch user interface but also for its unique ability to let users easily purchase, download, and use thousands of different applications."

Some developers were working under the radar on programs for the iPhone before the App Store, although they could only be run on specially hacked handsets – a process frowned upon by Apple. Now, by opening up the iPhone, Apple is encouraging a generation of DIY developers to turn from poachers to gamekeepers and get busy creating.

One of them is David de Niese, a 28-year-old banker who first caught the programming bug at school. "We had a Commodore 64, but my mum and dad would limit the time my brother and I could use it," says De Niese. "While my brother used the time to play games, I'd use my two hours for development. Every Saturday my mum would drop me off at the library, and I'd spend my time reading the Commodore 64 Programmer's Reference Manual, the bible writing code."

Despite studying computer science at university, De Niese went into a banking job when he graduated and programming stayed a hobby, but when he heard Apple's announcement about the App Store, he decided he had to be involved. "When the announcement was made, I thought it was brilliant as it is such a great device," says De Niese. "For a hobby programmer they're a godsend as they have all this hardware inside you can play around with – accelerometers, GPS, a touch-screen display."

With his programming experience, learning Objective C – the "language" on which iPhone applications are built – didn't prove too challenging for De Niese. "It took me five days to pick up the basics, and then I just started experimenting with a few very simple apps to learn the platform.

"It would be difficult for someone without any programming experience to start programming the iPhone," says Niese." But Apple assist with some well-structured frameworks but there is a lack of information out there in bookstores and on the internet. As the iPhone becomes more mature the information will start appearing and people will start sharing knowledge on the internet. Initially, people weren't keen to share information because of non-disclosure agreements that were put in place during the launch. Now books are starting to appear on Amazon and other internet websites. I would recommend new-comers to start off with Java or Objective C to gain a foundation, and then to move on to iPhone development."

After paying $99 (£66) to Apple for a licence, De Niese's first application – My Moving Maps, which tracks you and your friends' location – took just two weeks to write. He submitted it to Apple, which reviews each application before allowing it to be published. Once they had accepted it, the program was available to buy from the App store – and within weeks, My Moving Maps was being sold around the world to millions of iPhone users.

De Niese was astonished by how the program he wrote in his spare room in his home in Hertfordshire could spread to countries as far away as Kazakhstan and Hawaii. "I haven't seen anyone else like Apple who lets you put your app out there in the world," he says. Within 24 hours the application was being used in every continent apart from Antarctica.

The ready-made distribution system also sorts out the financial side. My Moving Maps sells for £1.19 in the UK, and roughly the same in other countries, and Apple collects the money for De Niese, as well as advertising the application. Of course, Apple isn't doing this for altruistic reasons. They take 30 per cent of each sale, but after tax this can still leave a tidy sum for the developer. "I came to this thinking this is just a bit of fun," says De Niese, "but you could make a living, although to be honest it wouldn't be the best."

It seems like the perfect situation – Apple gets countless new applications which drive the popularity of the iPhone up, while developers get a chance to make a bit of money. Yet the set-up isn't without its critics. In a recent article for the tech-news website The Register, American blogger Ted Dziuba described the App Store as "a classic protection racket", pointing to the fact that any application for the iPhone has to be sold through the App Store. "What happens when Apple's 30 per cent [cut] becomes 35 per cent?" he warns. "With nothing to stop them, Apple is in a great position to bleed developers dry."

Apple has also been attacked for the control they have over which applications they approve. This is where Google, which is hoping to seriously challenge Apple, wants to gain some ground with the launch of their new mobile platform, Android. Google's own application store opened last month, and key to its plans is the freedom developers will have.

Whereas Apple can reject applications for a number of different reasons, developers for Android only need to register, and from then on no further approval is required. And applications can be installed without even using the store. Google's Eric Chu wrote in a blogpost in August that they "feel that developers should have an unobstructed environment to make their content available". A dig at Apple?

A rethink of the approval process by Apple would also give developers more freedom, believes De Niese: "What Apple needs to do is have someone who you can go to when you come up with an application idea. You can ask them: 'I'm going to spend my time writing this application, are you likely to approve it?' Right now people are writing applications that take no longer than two or three weeks to create for fear of Apple rejecting it, but if Apple gave approval first I would spend one or two months on one. Then the value and the quality of the applications will soar."

For the future, De Niese – who has just released a new puzzle game called Larry's Gold – plans to keep working in his home office, and try to produce a new application every month. "It's something I'd be doing anyway and now I get the opportunity to do it on a platform which is a great toy," he says. "I don't understand why more people aren't doing it – the potential of the iPhone hasn't yet been grasped."

Added extras: iPhone apps to get your hands on

Free

Backgrounds

Find the perfect background to personalise your iPhone with one of more than 1,000 images on this program.

Virtual Zippo Lighter

Possibly one of the most pointless applications available, nonetheless the flame from this virtual lighter reacts to movement and the lighter itself can even be personalised.

Black Mamba Lite

There are a lot of free applications, like this top-down racer with just one track, that are designed to attract users to the full, paid-for version of the game.

Google Earth

You can now explore the globe on your phone with Google's revolutionary program which has all the satellite imagery of the desktop version.

DigiDrummer Lite

Bang the drums on your iPhone with this nifty application that lets you create your own beat with your fingers.

Pay for

Moto Chaser

A 3D-racer that costs a mere 59p, you can burn rubber through nine different tracks in a race against the clock, fighting other motorbikers along the way.

Ocarina

Transform your iPhone into a true musical instrument, as you play the Ocarina with a combination of touch, movement and your breath.

Flick Fishing

A fully 3D fishing simulator that lets you attempt to land the catch of the day at six different locations – you can even brag to your friends via email about the whopper you've landed.

iHunt.........

Pack up your shotgun and rifle, and go hunting for deer – or clay pigeons if you'd prefer – in this shooting simulator.

iChess

A simple, no-fuss interface makes this chess game easy to play, and you can face-off against the computer or your friends.