When the iPhone was originally introduced back in 2007, there was no native SDK. Apple claimed that one wasn’t needed and that applications for the device should be built as web applications using JavaScript, CSS, and HTML. This didn’t go down well with the developer community; they wanted direct access to the hardware and integration with Apple’s own applications.

Only a few months after the iPhone’s release, the open source community had accomplished something that many thought impossible. Despite Apple locking the device down, developers had gained access, reverse-engineered the SDK, and gone on to build a free open source tool chain that allowed them to build native applications for the device. At one point, it was estimated that more than one-third of the iPhones on the market had been “jail broken” by their users, allowing them to run these unsanctioned third-party applications.