for frontend and backend program, Router can be described, input a string like path(or indentifier), the program will execute some dedicate service(or function) or display some dedicate UI modules. Briefly, the progress is , you describe what you want , the router will give what you want.
make an analogy, nested Routes is like the catelog of a book,that is a nested structure.The logical nested structure is benifitful for searching what you want.
declare routes as part of your app’s initialization before any rendering takes place. React Router also followed that lead up until v4.
When we say dynamic routing, we mean routing that takes place as your app is rendering, not in a configuration or convention outside of a running app.