This illustration shows three versions of the same subtree. The root of the subtree represents the base of the search. It has three children. One of the children has two children of its own.

The version of the subtree on the left has a box around the base, indicating that the search is limited only to the base of the subtree. The version of the subtree in the middle has a box around the three immediate children of the base, indicating that the search is limited to them. The version of the subtree on the right shows a box around the entire subtree, indicating that the search extends to the entire subtree, including the base object.