Why do sidewalk have built in cracks every few feet?

Sidewalks have built-in cracks, often referred to as expansion joints, to allow for the natural expansion and contraction of the concrete due to temperature changes and moisture. These joints help prevent the concrete from cracking unevenly, which can lead to structural damage. Additionally, they facilitate drainage and can help manage the natural settling of the ground underneath. Overall, these cracks are essential for maintaining the longevity and safety of the sidewalk.