Backlash is the tiny clearance available between adjoining gear teeth. This space exists to avoid the machine from jamming and allow easy lubrication. Nevertheless, while machining, this space can cause the measurement to be inaccurate and the design to be unresponsive. So, backlash is both necessary and a problem. In CNC machining, backlash is especially problematic as it can be difficult to trace and even more difficult to compensate. Sometimes the clearance between adjoining gear teeth is not the only reason for backlash.