[Chinese (Mandarin) gngfu, skill, art  : gng, worker, work + f, man, laborer.]

Kung Fu, also known as Gung Fu, are modules of codified practices or traditions of unarmed and armed combat. They are often taught today with the goal of developing both the mind and the body of the practitioner.

"Kung Fu", translated  means mastery of a skill.  The Chinese term for martial arts is Wu Shu. Wu Shu's exact origin is arguable. Some historians say it surfaced in the Shang Dynasty (16th Century B.C.) other attribute it to the period of the Contending States (475-221 B.C.)

As it was said
In about 539 AD, a holy man named Bodidarama left his monastery in India to spread the Buddhist faith to China. After traveling hundreds of miles to reach Northern China and crossing the Himalayan mountains (Even today with our technology and equipment is an incredible feat) he headed North to Loyang, the capital of Henan Province.

There of course he found the Shaolin (Temple) Bodidarama sought entrance to the temple but was not granted entrance (as many sought entrance for various reasons).

Bodidarama was determined to enter and see the Shaolin Ssu. He located to a nearby cave on the side of a mountain, where (it is said) he sat in meditation facing a stonewall. He sat facing the wall for most of the next nine years at the end of which Bodidarama's deep blue piercing eyes had apparently drilled a gaping hole in the cliff wall.

9 years stairing at a wall will grant you access to the temple
Upon gaining entrance to Shaolin. Ta Mo (as he was now called by the Chinese) saw that the monks were weak and could not perform the rigorous meditations he expected that Buddhist Monks should be practicing. Whilst meditating they often fell asleep or were very restless and were not achieving inner calm or peace (which is required to reach Enlitenment, that for which all Buddhist strive!).

He spent some time in seclusion pondering the problem. Considering the time and health awareness at the time Ta Mo came to a staggeringly accurate conclusion, that the monks were not fit to meditate. With this in mind he started working on a solution; he created three principles of exercises.

These in-place exercises were later transcribed by monks as;

a.       The Muscle Change Classic

b.       The Marrow Washing.

c.     The Eighteen Hand Movements.

So Many Styles
Many styles of Kung Fu revolve around the ideas of nature. The ancient masters often developed their techniques by observing the world around them. Animals and insects provided the foundation for many systems of Kung Fu. Other factors were philosophy and religion.

Kung Fu itself has fragmented incredibly, with as many as 1500 styles practiced. Some emphasize circular hand techniques and a flowing, rhythmic fighting style others have long sweeping motions and emphasise power and strength. 

By the 13th Century AD Kung Fu had developed and expanded throughout Asia. In Japan it became Karate, and in Korea, Taekwando. All current styles of the martial arts are an off shoot of the original Shaolin Kung Fu.