Web workers offer a means to execute JavaScript code in a separate thread, independent of the main browser thread, enhancing performance in complex applications by preventing browser stalling during computationally intensive tasks. Despite advances in CPU speed and memory, web workers remain relevant for tasks that can become resource-intensive when executed concurrently with other processes on a user's system. They facilitate two-way communication with the main thread via the postMessage() function and a message event handler, ensuring data is passed by copy to prevent conflicts. Use cases include data prefetching, processing large data sets, and image processing. Web workers are demonstrated in examples like game collision detection, where they manage computationally heavy tasks, and image thresholding, where they handle both CPU and memory-intensive operations. They are supported by major browsers, ensuring compatibility and improved user experience without compromising the main thread's responsiveness.