Yo-Yo

A Yo-Yo is a popular toy consisting of two identical wood, metal, or plastic discs, which are connected by an axle around which a string is wound.
Although its popularity has waned at times, the yo-yo has been a fixture of American popular culture for the past 100 years. Yo-yo contests are held yearly, at which experts showcase the latest tricks, techniques and technologies. How it Works The user holds on to one end of this string, and gently "throws" the yo-yo, which travels down the string as it unwinds from the axle. Upon reaching the end of the string, the toy continues to spin, providing it with gyroscopic stability. Depending on the design of the yo-yo, the spinning axle may grip the string and automatically rewind the yo-yo, or it may require a small jerk to return to the user's hand.
History of the Yo-Yo

The first evidence of the yo-yo hails from Ancient Greece in the form of a clay pot painted with the image of a boy playing with a yo-yo that dates to around 500 BC.
The modern yo-yo, which, due to the string being looped, and not tied to the axle, allows the yo-yo to "sleep," was designed in the Philippines and brought to the United States by Pedro Flores, who opened the Yo-Yo Manufacturing Company in Santa Barbara, California in 1928.
Donald Duncan bought Flores' company in 1930, and through a variety of marketing campaigns, made the yo-yo one of America's most popular toys. Duncan enjoyed a monopoly on the yo-yo market for the next 30 years, culminating in 1962, when he sold 45 million units. Duncan sold his company in 1965 after losing the trademark on the term "yo-yo." Technological Advancements In the 1970s, yo-yo companies started manufacturing yo-yos with weighted rims, which allowed for longer spin time. In 1978, Tom Kuhn patented the "No Jive 3-in-1" yo-yo, the first "take-apart" design, which enabled yo-yo players to change the axle.
In 1980, Michael Caffrey invented the first yo-yo with a centrifugal spring loaded clutch mechanism, which caused it to return automatically once the spin speed dropped below a certain level.
In the 1990s, this technology was further improved by the addition of a ball-bearing axle, which further increased spin time.
Fast Facts:
1. Donald Duncan's birthday, June 6 is National Yo-Yo Day
2. On April 12, 1985, the yo-yo became the first toy in space
3. Second oldest surviving toy, next to the doll
4. Believed to have originated in China
Contests/Exhibitions:
1. International Yo-Yo Open: August 8—9, 2008, New York City
2. 2008 World Yo-Yo Contest: July 31—August 2, 2008, Orlando, Florida