A [[yo-yo]] A '''yo-yo''' (also spelled '''yoyo''') is a [[toy]] which in its simplest form is an object consisting of an [[axle]] connected to two [[cylinder|disks]], and a length of string looped around the axle, similar to a slender [[wikt:spool|spool]]. It is played by holding the free end of the string known as the handle (usually by inserting one finger into a [[slip knot]]) allowing gravity or the force of a throw to spin the yo-yo and unwind the string (similar to how a [[pullstring]] works), then allowing the yo-yo to wind itself back to one's hand, exploiting its spin (and the associated [[rotational energy]]). This is often called "yo-yoing". First made popular in the 1920s, yo-yoing remains a popular pastime of many generations and cultures. It was first invented in [[ancient Greece]].
