A shoulder is like the little edge of the road, kind of like the side of a sidewalk. It’s usually a little bit wider than the white line that separates the road from the spaces next to it, like the grass or the curb. It's a safer place for a car to pull over if it has a problem or if the driver needs to take a break. Sometimes, the shoulder is also used by bikers or pedestrians to move safely around the road. So, it’s important to pay attention to the shoulder when you're driving and be careful, just like you would when you're walking on the sidewalk.