Cocoa Touch is a user interface framework used for developing applications on iOS devices, such as iPhones and iPads. It provides the necessary tools and components to create visually appealing and interactive apps, including buttons, sliders, and gestures. This framework is built on top of Cocoa, which is used for macOS applications. Cocoa Touch supports features like touch-based input, multitasking, and notifications, making it essential for developers who want to create seamless experiences for users on mobile devices.