A roundabout is a type of road junction at which traffic enters a one-way stream around a central island. In the United States it is commonly known as a “rotary” or a “traffic circle”, but sometimes is technically called a modern roundabout, in order to emphasize the distinction from the older, very much larger type of traffic circle which usually had poor or no visibility across the central island.
In countries where people drive on the right, the traffic flow around the central island of a roundabout is counterclockwise. In countries where people drive on the left, the traffic flow is clockwise.
Overall, roundabouts are statistically safer than both traffic circles and traditional intersections, with the exception that cyclists have a significantly increased crash rate at large roundabouts. Roundabouts do not cope as well with the traffic on motorways, highways, or similar fast roads.