To keep the iPhone a secure device that performs well, Apple originally decided it would only run Apple-developed applications. While there is a good reason for this argument, it didn’t stop enterprising hackers from figuring out how they can both add and create custom applications for the iPhone.

After the iPhone was on the market for a few months, Apple realised that there was a budding community of people out there who wanted to create applications for the iPhone, so they partially relented on their strict stance by allowing developers to create web applications that ran through the web application Safari.

By the time they changed their stance, the iPhone had already been hacked and a wealth of various programs had been created to take advantage of the iPhone’s amazing power and intuitive interface.

Vetoed Applications
The launch of the iTunes iPhone App Store meant that there isn’t as great a need for jailbroken iPhones, but there are many great applications that Apple won’t allow into the App Store, such as MMS applications, video recorders and software that modifies the look and feel of the iPhone’s user interface. To get such applications, jailbreaking the iPhone is the only option, but this needs to be weighed against the risk of voiding the iPhone warranty and the risk of permanently damaging the iPhone in the process.