Steel balls have been used for many years in various physics experiments and are almost universally described incorrectly by physicists as “ball bearings.” It seems that physicists have chosen this term through common usage, without recognising that a ball bearing is actually a bearing rather than a ball. The bearing is constructed with an inner and outer race containing a number of steel balls that help to reduce friction by rolling around the race. The balls themselves are not ball bearings. Rather, they are bearing balls usually made of steel, but ceramic balls can also be used, allowing the bearing to spin faster since the balls are lighter. A common application is to support a wheel that rotates on an axle. Ball bearings can also be found in modern yo-yo's and fidget spinners.