General query about Octree Model

[KeenToLearn]

Hello All,

I have gone through some of the online material regarding to Octree model,but still I have some basic queries regarding Octree Model

1) What is the exact definition of a leaf in an Octree?

2) What is the exact meaning of this line? - "Octrees are most often used to partition a three-dimensional space by recursively subdividing it into eight octants."

3)Also,the concept of generating Octree Model from a facet Model

Thanks in Advance