Multi-threading is a programming technique that allows a single program to perform multiple tasks simultaneously. By dividing a program into smaller parts called threads, each thread can run independently, making better use of the computer's resources. This can lead to improved performance, especially in applications that require heavy processing or need to handle multiple tasks at once. In a multi-threaded environment, threads share the same memory space, which allows them to communicate and share data easily. However, this also means that developers must manage potential issues like race conditions and deadlocks, where threads may interfere with each other, leading to errors or inefficiencies.