iPhone and iPod touch are sophisticated devices that combine the revolutionary Multi-Touch interface with powerful features, such as email and instant-messaging capability, a full-featured web browser, iPod, and, in iPhone, a mobile phone. iPhone OS is the system software that runs on iPhone and iPod touch. With the advent of the iPhone SDK, these powerful features are extended to include significant developer opportunities. In addition to creating web content for use on iPhone OS–based devices, developers can use the iPhone SDK to create native applications people can store and use on their devices.
Read this document to learn about the range of application types you can develop for iPhone OS and the human interface design principles that inform all great software. In this document you also learn how to follow those principles as you design a superlative user interface and user experience for your software. Whether you’re an experienced computer application developer, an experienced mobile-device application developer, or a newcomer to the field, the guidelines in this document will help you produce iPhone applications users want.