To cut or not to cut… that is the question.  During the hydration, or curing process of concrete, the concrete shrinks a little which stresses the concrete, possibly to the point of forming narrow cracks.  These cracks are called “shrinkage” or “plastic” cracks and can be controlled by cutting the concrete into small enough sections, so the cracks hopefully form in the cuts.  Movement style cracks due to the shifting ground caused by frost or settling are very difficult to control by cutting.  Concrete cracks to relieve the pressures placed upon it, and the location of the control cut may not be the location of the most stress.  Cracks often appear right next to or crossing control cuts which you can easily see when you are out for your next walk.