However, a short refesh of trees can't hurt, so you might read this chapter to refresh your knowlage. If all this is new to you you should read the entire article, even if you don't understand it. After you saw an example how to use them you'll surely understand them. A Octree is a tree-structure which contains data. The data is stored in a hirarchical way so that you can search an element very fast.
Every tree has at least a root-node which is the anchor of all subnodes.
Every Node has pointers to 8 subnodes. Insertion of Data Data is stored in a binary way. Now lets insert a color into the tree. This byte is an index of the child-nodes we have. Now we look at the child node pointed by our binary index.