Juggling was the skill of keeping several objects in motion using one's hands. It was sometimes considered an artform similar to dance, and was often practiced before an audience as a form of entertainment.
The Juggler was a character featured in a holodeck holoprogram that simulated the Parallax colony. He practiced the art of juggling. Lwaxana Troi introduced Alexander Rozhenko to this holodeck simulation of the colony in 2368. (TNG: "Cost of Living")
Ensign Pablo Baytart, a Starfleet officer aboard the Federation starship USS Voyager, was a skilled juggler and was one of the first featured guests on A Briefing with Neelix in 2372. In his appearance he juggled a collection of PADDs, hyposprays and phasers. (VOY: "Investigations")