Other than dolls, yo-yos are the oldest toy in the world. The yo-yo likely goes back to ancient China, and we can definitely trace it to 500 BC in Greece; the National Museum in Athens has an ancient yo-yo and artistic images of Greek yo-yoers.
Eventually, trade routes took the yo-yo around the world, and the toy popped up in Egypt, India, and Western Europe. The yo-yo was especially popular in France around the time of the French Revolution, and one 18th century painting shows King Louis XVII playing with a yo-yo.
The yo-yo largely faded from Western use, however, until a Filipino-American named Pedro Flores (or Tony Flor) began producing the toy. The yo-yo had remained popular in the Philippines (the word “yo-yo,” which means “come come” is likely derived from a Filipino word), and the Filipinos had improved the toy’s design, adding a slipstring over the axle to allow easier motion.
In any case, Flores opened a shop in 1928 with twelve yo-yos, and by November 1929, he was producing 300,000 yo-yos per day. The next year, he sold the rights to Donald Duncan, who made yo-yos a national phenomenon, particularly during the 1960s. Duncan remains the official name of the yo-yo manufacturer, but the company is actually owned by Flambeau Plastics and no longer owns the term yo-yo.
Today, manufacturers continue to sell the basic yo-yo design for easy fun, but they are also releasing yo-yos with modern designs that help yo-yoers perform complex tricks. These complex tricks appear at yo-yo competitions, such as the national championships in Chico, California, and the world championships in Orlando, Florida. Yo-yo competitions have multiple divisions (e.g. one yo-yo or two yo-yos) and are divided into compulsory tricks and a freestyle section set to music.