Simply put, the server side refers to response, such as sina, 163, sohu. Client refers to the request, like you and I end client PC. Generally, when we visit a large website, it is us, that is, the client makes a request, and then the other server segment responds, and the result is to return the page path to us, and then we see the page according to the path. What's complicated here is that there are many kinds of things sent to us, but the principle is the same, one request, one response.