Multi-threading is a programming technique that allows a single process to execute multiple threads concurrently. Each thread represents a separate path of execution, enabling tasks to run in parallel within the same application. This approach is commonly used to improve the performance and responsiveness of software, especially in applications that handle multiple tasks simultaneously, such as web servers or user interfaces. By efficiently utilizing system resources, multi-threading can help reduce processing time and enhance the user experience. However, it also introduces challenges like thread synchronization and data sharing, which require careful management to avoid errors such as race conditions.