Juggling is a physical skill, performed by a juggler, involving the manipulation of objects for recreation, entertainment, art or sport. The most recognizable form of juggling is toss juggling. Juggling can be the manipulation of one object or many objects at the same time, most often using one or two hands but other body parts as well, like feet or head. Jugglers often refer to the objects they juggle as props. The most common props are balls, clubs, or rings. Some jugglers use more dramatic objects such as knives, fire torches or chainsaws. The term juggling can also commonly refer to other prop-based manipulation skills, such as diabolo, plate spinning, devil sticks, poi, cigar boxes, contact juggling, hooping, yo-yo, hat manipulation and kick-ups.

The words juggling and juggler derive from the Middle English jogelen ("to entertain by performing tricks"), which in turn is from the Old French jangler. There is also the Late Latin form joculare of Latin joculari, meaning "to jest". Although the etymology of the terms juggler and juggling in the sense of manipulating objects for entertainment originates as far back as the 11th century, the current sense of to juggle, meaning "to continually toss objects in the air and catch them", originates from the late 19th century.

From the 12th to the 17th century, juggling and juggler were the terms most consistently used to describe acts of magic, though some have called the term juggling a lexicographical nightmare, stating that it is one of the least understood relating to magic. In the 21st century, the term juggling usually refers to toss juggling, where objects are continuously thrown into the air and caught again, repeating in a rhythmical pattern.

According to James Ernest in his book Contact Juggling, most people will describe juggling as "throwing and catching things"; however, a juggler might describe the act as "a visually complex or physically challenging feat using one or more objects". David Levinson and Karen Christensen describe juggling as "the sport of tossing and catching or manipulating objects [...] keeping them in constant motion". "Juggling, like music, combines abstract patterns and mind-body coordination in a pleasing way."

The earliest record of juggling is suggested in a panel from the 15th (1994 to 1781 B.C.) Beni Hasan tomb of an unknown Egyptian prince, showing female dancers and acrobats throwing balls. Juggling has been recorded in many early cultures including Egyptian, Nabataean, Chinese, Indian, Greek, Roman, Norse, Aztec (Mexico) and Polynesian civilizations.

Juggling in ancient China was an art performed by some warriors. One such warrior was Xiong Yiliao, whose juggling of nine balls in front of troops on a battlefield reportedly caused the opposing troops to flee without fighting, resulting in a complete victory.

In Europe, juggling was an acceptable diversion until the decline of the Roman Empire, after which the activity fell into disgrace. Throughout the Middle Ages, most histories were written by religious clerics who frowned upon the type of performers who juggled, called gleemen, accusing them of base morals or even practicing witchcraft. Jugglers in this era would only perform in marketplaces, streets, fairs, or drinking houses. They would perform short, humorous and bawdy acts and pass a hat or bag among the audience for tips. Some kings' and noblemen's bards, fools, or jesters would have been able to juggle or perform acrobatics, though their main skills would have been oral (poetry, music, comedy and storytelling).

In 1768, Philip Astley opened the first modern circus. A few years later, he employed jugglers to perform acts along with the horse and clown acts. Since then, jugglers have been associated with circuses.