Hierarchical inheritance is when more than one class is inherited from the base class. All features that are common in child classes are included in the base class under hierarchical inheritance. Physics, Chemistry, and Biology, for example, are all derived from Science class.
There are three types of inheritance: single, multiple, and multilayer inheritance. Only single inheritance is supported in PHP, which means that only one class can be derived from a single parent class.
A group of people or objects organised in order of rank, or the people who rank at the top of such a system, is defined as a hierarchy. The corporate ladder is an example of hierarchy. The numerous ranks of priests in the Catholic church are an illustration of hierarchy.
To create hierarchical inheritance, at least three classes are required: two derived classes and one base class. Two child classes can inherit the properties of the common parent class in this situation.
An effective hierarchy holds executives accountable for their actions and allows them to replace failed employees with new ones, often through internal promotion. That is how hierarchy, including owners, managers, and employees, contributes to the overall success of the company.