This document summarizes different types of iPhone applications and design guidelines. There are three main types of iPhone applications: native applications, web-only content, and hybrid applications. Native applications resemble built-in apps and go through Apple's approval process. Web-only content is viewed through Safari and has no approval needed. Hybrid apps combine native and web features and go through the approval process. The document also discusses application styles like productivity, utility, and immersive apps and provides guidelines for gestures, simplicity, and branding.