The yo-yo is a toy consisting of a slightly flattened, round piece of plastic, wood, metal, etc., having a deep groove in which a string is wound. There is a loop at the free end of the string. It is played by placing the loop over the middle finger, grasping the yo-yo, then throwing it with a smooth motion. As it spins it in effect becomes a gyroscope, permitting various tricks to be performed. By flicking the wrist, the yo-yo can be made to return to the player's hand, with the cord again completely wound into the groove.
The yo-yo was introduced to the USA in 1928 by Pedro Flores when he opened the Yo-Yo Manufacturing Company in Santa Barbara, California. Flores later opens a location in Los Angeles (1929). Donald Duncan, Sr. purchased rights from Flores in 1930.