Insert picture description here for routing
1. Concept: 
routing refers to the process in which a router receives a data packet from an interface,
directs it according to the destination address of the data packet, and forwards it to another interface. In other words, the router is responsible for transferring data packets in the middle, and the connection between the host and the host is connected through one or more routers.
Insert a picture here to describe the
route: it is a route, as can be seen from this English word, it is singular. Home button => home content, this is a route; about button => about content, this is another route.
routes: routes is a set of routes, combining each of the above routes to form an array. [{home button => home content}, {about button => about content}] 3⃣️ router: router is a mechanism, equivalent to a manager, which manages routing. Because routes only define a set of routes, where it is placed is static, what should I do when a request comes in? What happens when the user clicks the home button? At this time, the router is working. It searches the routes to find the corresponding home content, so the home content is displayed on the page.
