A bottleneck is a stage that limits the throughput of a process under particular conditions. Improving a different stage may create a larger queue without increasing completed output. The constraint can move as conditions change. Map the steps and measure how work arrives, waits, and finishes. Distinguish processing time from waiting time. Look for repeated accumulation rather than assuming the busiest-looking person is the constraint. Check whether rework or missing information is creating extra demand. In a small printing workflow, approval delays may hold up jobs even when the printer itself is fast. Possible changes include clearer submission requirements or a scheduled review window. Test the effect on the whole process, including quality and workload. Practice: Draw a four-stage process and mark where work waits. Propose one measurement that would help determine whether that stage actually limits completion.