Hairpin turn

A hairpin turn (also hairpin bend, hairpin corner, or just hairpin), is a very tight corner. It makes a vehicle turn almost 180° to continue on the road. It gets its name from the way it looks like a hairpin or bobby pin. Hairpin turns may be called switchbacks in American English.
Hairpin turns may be built when a road or path climbs up or down a steep slope. This allows the path to travel the slope with a smaller slope. Hairpin turns may be used in race tracks to slow down the race cars after a long, fast straight.