Kotlin Coroutines are a feature in the Kotlin programming language that simplify asynchronous programming. They allow developers to write non-blocking code in a sequential manner, making it easier to manage tasks that take time, such as network requests or database operations. Coroutines help improve app performance by freeing up resources while waiting for these tasks to complete. Using coroutines, developers can launch lightweight threads called coroutine builders, which can be paused and resumed without blocking the main thread. This leads to smoother user experiences in applications, as the user interface remains responsive even during long-running operations.