Understanding Global Illumination

[jeang]

Hello All,

I am trying to understand the Global Illumination setting so that I am able to go a little beyond trial and error.
Here is a simple scene where all materials including the Ground is made of a Glossy plastic (no rugosity).
In one case the GI is ON and the other is OFF.

The manual states:
Global Illumination Bounces
When Global illumination is on, Global Illumination Bounces allow you to control the maximum number of times the light is reflected diffusely as it passes through the scene.

This said, not sure I can interpret this in light of the results ? Would this mean: Indirect lightening made of diffuse rays ? Not certain where the diffuse rays would come from in the scene enclosed.

Is there any more detailed explanations available that would assist in understanding these settings better ?

Many thanks,
Jean