The image shows the terminologies used in a table hierarchy. The topmost node or the root node is A. B and G are children of A. Since they are children of the same parent node, B and G are siblings. Node B in turn has 2 children, C and D. C and D are siblings. Node G has 2 children, H and I. H and I are siblings. C, D, H and I are grandchildren of node A.