In a hierarchical classification task, the classification problem can be resolved by dividing the output space into a tree. In that tree, parent nodes are divided into multiple child nodes. The process persists until each child node depicts a single class. Several methods have been proposed based on the hierarchical classification technique. Computer vision is an example of such areas where recognizing pictures or written text are something that use hierarchical processing does. An extensive discussion on this classifier is out of the scope of this chapter.