In addition, your developer and distribution certificates will be revoked. Finally, any applications you have on the iTunes App Store will be removed. You have two options when enrolling in the iPhone Developer Program. Most people will want to register for the Standard Program, which costs $99 per year. This will allow you to create free--or, once you've filled out some paperwork, commercial--applications for the iPhone and iPod touch, and distribute them either via the App Store or via the ad hoc distribution channel where you provide both the application binary and a provisioning certificate to the end user. The more expensive Enterprise Program, at $299, is intended for companies with more than 500 employees that wish to create applications for in-house distribution. While this program allows you to distribute your applications inside your own company, it does not allow you to publish them for sale on the App Store. If you're thinking about selling your applications to the public, you need the Standard Program. Installing the iPhone SDK Once you have registered as an iPhone developer you can log in to the iPhone Dev Center and download the iPhone SDK. At the time of this writing, Apple combined the iPhone SDK and Xcode into a single download. It is possible that in future releases you may need to install Xcode first, and then install the iPhone SDK from a separate installer. Newer prerelease beta versions of the SDK may be available to those enrolled in the iPhone Developer Program; however, the current stable version will be available even if you choose not to pay to enroll in the program. The combined download of the Xcode development tools and the iPhone SDK is around 2.5 GB in size. The combined bundle will be downloaded as a disk image file. After it downloads, the image should automatically mount; double-click on the iPhone SDK and Tools package file to install the SDK, as shown in Figure 1-1.