A nested category is a hierarchical list that can support sub-categories up to the `nth` level. Usually, you can use the list when designing applications such as e-commerce websites, accounting systems, animal kingdoms, geospatial data, and more. To better understand this model, think about a corporate ladder. At the top, you have the CEO. Then, there can be several departmental heads reporting to them. Then, from each department, you can have thousands of employees under the supervisory teams. ......