The yo-yo is a toy consisting of two equally sized and weighted discs of plastic, wood, or metal, connected with an axle, around which string is wound. First becoming popular in the 1920s, "yo-yoing" still enjoys a following of children as well as adults. The yo-yo is usually credited as having been invented in the Philippines centuries ago. The name yo-yo is sometimes said to have derived from Tagalog, translating as "come-come". However, yo-yo is not a Tagalog word for anything (the word for "come" is halika); it is possible that the term came from another Philippine language. The term was first published in a dictionary of Filipino words printed in 1860.

The principal distinction between the Filipino design and previous, more primitive "back-and-forth" models is in the way the ^yo-yo is strung. One continuous piece of string, double the desired length, is twisted around itself to produce a loop at one end which is fitted around the axle. Also termed a looped slip-string, this seemingly minor modification allows for a far greater variety and sophistication of motion, thanks to increased stability and suspension of movement during free spin.