Free running or freerunning is a form of urban acrobatics in which participants, known as free runners, use the city and rural landscape to perform movements through its structures. It incorporates efficient movements from parkour, adds aesthetic vaults and other acrobatics, such as tricking and street stunts, creating an athletic and aesthetically pleasing way of moving. It is commonly practiced at gymnasiums and in urban areas (such as cities or towns) that are cluttered with obstacles.
The term free running was coined during the filming of Jump London, as a way to present parkour to the English-speaking world. However, the term free running has come to represent a separate concept, distinctly different from parkour — a distinction which is often missed due to the aesthetic similarities. Parkour as a discipline emphasizes efficiency, whilst free running embodies complete freedom of movement — and includes many acrobatic maneuvers. Although the two are often physically similar, the mindsets of each are vastly different
The founder and creator of free running, Sébastien Foucan, defines free running as a discipline to self development, following your own way, which he developed because he felt that parkour lacked enough creativity and self-expression as a definition of each free-runner to follow your own way.
http://en.wikipedia.org/wiki/Free_running