It is one of many ways to visually display a tree,[2][3] with examples dating back to the early 20th century.
Layouts are generated by working outward from the center, root.
The nodes for level 1 can be distributed evenly, or weighted depending on the number of children they have.
For subsequent levels, the children are positioned within sectors of the remaining space, so that child nodes of one parent do not overlap with others.
Since the length of each orbit increases with the radius, there tends to be more room for the nodes.