Tricking is a word used to describe the combined movements of Martial arts, Capoeira, Breakdancing, and Gymnastics.
We call the movements used in combos or sequences, tricks. Its a free flow style where you can do anything you would like, the main goal being able to combine moves one after the other with no walking or running in between, only tricks.
Anyone can do it, big or small, short or tall. The idea behind how tricking is different then gymnastics, is that you'r using physics and momentum to perform a move, instead of blocking and power such as in gymnastics. Each person will have strengths and weaknesses in certain aspects (flexibility, power, speed, creativeness, flow), and tricking is a great way to exemplify what you're good at, and work on the lesser experienced aspects.