Unless you have been living in a whole on the internet than im sure you have seen many videos on sites such as YouTube of "monkey" like men jumping between massive gaps and vaulting over rails like they are part of an urban playground. Well this is correct, they are using the enviroment as a playground and the activity that they are participating in is called Parkour. The sport originated in the French town of Lisses some 18 years ago, when a young boy, "David Belle" began jumping  and using his enviroment in ispiration of his father. His father was a soldier who had returned from the Veitnam War and had told his son stories that he had escaped and used these skills to hide and gank opposing soldiers from trees, envious, Belle began to practise with friends and eventually progressed and later named the sport Parkour.

Draw a straight line on a map of your hometown. Start from point A and go to point B. Don’t consider the elements in your way (barriers, walls, wire fences) as obstacles. Hug them: climb, get over, jump, let your imagination flow. You are now doing Parkour. (David Belle, Urbanfreeflow 2004).

It’s also to know how to deny evidences, to keep a critical acumen. Example: the streets. A marked out route, where we no longer need to wonder if we must take it or not. It’s there; we take it, that’s all. (David Belle, Urbanfreeflow, 8 June 2004)

Parkour, is a practise that involves fluency, instincts, and relfexibilty. It can be seen as a type of obstacle coursing using your enviroment and it should be unstood that  Parkour is not just about impressing, it is about self gain, confidence and mental + phsyical strength. It is a general misconception that small obstacles are not Parkour because they do not "impress" however a small gap on a low level is just as relevent as a 10 meter high, 5 minute wide roof gap. 

The obstacle is the path.

One thing that will become present once you begin training parkour is the ability to see things in a different perception. Before training parkour a normal bar would appear to be nothing more than a utility to help you up a set over strairs or down a ramp, however once you inherit the "parkour eye" that bar will suddenly become vaultable or you will be able to do an underbar. These things are something that you develope once you begin training. 

    One thing that i personally love about parkour is the fast rate of progression. You can quite literally watch your self progress over a series of training sessions. Ever session increases your mental and phsysical capabilites and also makes Parkour extremely rewarding.

'Do not follow where the path may lead, go instead where there is no path and leave a trail.'

This is very simple and easy, start training. Walk out to your backyard and just start training. 

There are also quite a few sites in which you can meet other tracer (person who trains parkour) which include

www.urbanfreeflow.com

www.parkour.net

www.sydpk.com