The document discusses using a shared C# codebase across mobile and server platforms. It allows for 100% native API access on iOS, Android, and Windows while sharing backend code. It also enables offline sync functionality across these platforms using REST APIs, Azure Mobile Apps, and services like SQL, MongoDB, Office 365 APIs. The document provides code examples for creating a mobile service client, defining data tables, and performing CRUD operations to get, add, and modify data from the tables.