The diabolo is a juggling or circus prop consisting of an axle and two cups (hourglass/egg timer shaped) or discs derived from the Chinese yo-yo. This object is spun using a string attached to two hand sticks ("batons" or "wands"). A large variety of tricks are possible with the diabolo, including tosses, and various types of interaction with the sticks, string, and various parts of the user's body. Multiple diabolos can be spun on a single string.
The Diabolo is derived from the Chinese yo-yo encountered by Europeans during the colonial era. However, the origin of the Chinese yo-yo is unknown. The earliest mention of the Chinese yo-yo is in the late Ming dynasty Wanli period (1572–1620), with its details well recorded in the book Dijing Jingwulue by the Liu Tong. The book refers to Chinese yo-yos as "kong zhong" ('air bell').
Chinese yo-yos have a longer axle with discs on either end, while the diabolo has a very short axle and larger, round cups on either end. Diabolos are made of different materials and come in different sizes and weights.
The name "diabolo" was coined by Belgian engineer Gustave Philippart, who developed the modern diabolo in the early twentieth century, although credit has also been given to Charles Burgess Fry (The Outdoor Magazine in 1906) or Fry and Philippart. The ODE gives the term's origin as from ecclesiastical Latin diabolus (devil) via Italian, reflecting the older name, "The devil on two sticks".
The most basic act of diabolo manipulation is to spin it on the string. "The string is placed between the circles, but in order for the diabolo to balance, it must maintain a spinning motion, much like a yo-yo."
Typically, the player pulls the stick in his or her dominant hand so that the string moves along the axle, turning it. "The player...swing[s] the string right and left." By doing this repeatedly and rapidly the diabolo rotates faster. The diabolo spin can be accelerated more quickly using various methods: the 'whip' rotates the diabolo faster by moving one handstick in front of the user's body and past the other handstick, the 'wrap' rotates the diabolo faster when the user wraps a loop of the string around the axle. Both methods increase the amount of string contact with the axle in any given time.
To spin the top, you raise and lower the sticks alternately, with a quick backward shift of the string at the end of each rotating impulse. When the speed is great enough to stabilize the top in flight, just whip the sticks apart to toss it into the air. As the spool comes down you catch it on a sloping string and let it roll down into slack bunched near one end.
Once spin speed is increased to a sufficient level that the diabolo is stable, the user can then perform tricks. "Skillful players can set it whirling at a rate of 2,000 revolutions a minute, it is said." Depending on how long a trick takes to perform, the user will normally have to spend some time increasing the spin speed of the diabolo before performing other tricks. Skilled users can perform multiple tricks while maintaining the spin speed of the diabolo. "A skilled person [can] catch it, hurl it fifty or sixty feet into the air, then catch it again with little effort."
Check out this YouTube Tutorial on how to get started by @KineticCircus