Xamarin Forms allows developers to write cross-platform mobile apps for iOS and Android using shared C# code. It provides common UI elements like buttons and entries that are rendered natively on each device. While Forms handles much of the cross-platform code sharing, custom renderers may still be needed for platform-specific customization. The framework uses MVVM and messaging patterns to support data binding and communication between components. Xamarin Forms is best for new teams or products where a single shared UI is desired and the initial customization requirements are not extensive.