This is one of the best known images of photographer Henri Cartier-Bresson.
Cartier-Bresson legacy -part of it- is the search for the decisive moment: the quality of an snapshot that brings us to that situation and moment; just like being there.
The way Cartier-Bresson accomplishes this, the sheer simplicity of the photo, has fooled us all into thinking That's easy! (not, it is not).
A photo to enjoy and imitate.
This image can be seen at MoMA here.