Out-of-order execution is a technique used in modern computer processors to improve performance. Instead of executing instructions in the order they appear, the processor can rearrange them based on the availability of data and resources. This allows it to make better use of its time and complete tasks more efficiently. By executing instructions as soon as their required data is ready, the processor minimizes idle time. This means that even if one instruction is waiting for data, others can still be processed. Overall, out-of-order execution helps speed up computing tasks and enhances the overall performance of CPUs.