It is about running on a forrested terain.
At start ,the competitor is given  a map with a trail marked  by points which have to be checked in a certain order. The way between points is at competitor's will,depending on his ability to read and navigate on a map.
The scale of the map is usualy :  1 cm on map = 100....150m on terain.
The winner is the one who finishes the trail in the shortest time.
The ranking is made  by categories of age, separately for men and women.
There is an International Orienteering Federation. It is organising
the World championships and international orienteering events
the so called WRE (world ranking events)
You can find it at
On almost all orienteering events (competitions) in Romania any visitor (the man from the street) who wants to see by simple curiosity how  is it ,and is comming to the competition centre acording to invitation (see invitations link) he could be given a map with a trail for beginers the so called OPEN which is simple and can be made by walking even without a compass.
Those who are regular practicants of this sport in Romania are in number of about 800.
With those who come ocasionally they could be  4000.