National Yo-Yo Day is celebrated on June 6th of each year in honor of Donald Duncan Sr., the entrepreneur who brought mass-produced yo-yos to the United States. However, it was later found that Donald Duncan Sr.’s birthday is actually June 8th.
The yo-yo in its simplest form is an object consisting of an axle connected to two disks, and a length of string looped around the axle, similar to a slender spool. It is played by holding the free end of the string known as the handle (usually by inserting one finger in 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.
In the simplest play, the string is intended to be wound on the spool by hand; The yo-yo is thrown downwards, hits the end of the string, then winds up the string toward the hand, and finally the yo-yo is grabbed, ready to be thrown again. One of the most basic tricks is called the sleeper, where the yo-yo spins at the end of the string for a noticeable amount of time before returning to the hand.
Many yo-yo tricks are done while the yo-yo is said to be sleeping. One of the most famous tricks on the yo-yo is “walk the dog”. This is done by throwing a strong sleeper and allowing the yo-yo to roll across the floor, before tugging it back to the hand. English historical names for the yo-yo include bandalore (from French) and quiz. French historical terms include bandalore, incroyable, de Coblenz, emigrette, and joujou de Normandie (joujou meaning little toy).