As users of Education Network and 169, they can't directly visit foreign sites, and the network speed is surprisingly slow, so many network functions can't be used. The most typical example is that you can't use Icq, because the servers of Icq are all abroad and you can't connect directly. So the proxy server plays a vital role at this time.
Usually, when we visit a website, we connect directly to the destination host. If we use a proxy server, we can connect with the proxy server first, and then tell the proxy server our request (such as which page we want), and the proxy server will help us get it down. Generally, the proxy server has a large cache, which plays a buffering role, and it constantly stores the newly acquired data in the memory; If the data requested by the browser already exists in its local memory and is up-to-date, it will not retrieve the data from the Web server, but directly transfer the data in the memory to the user's browser, which can significantly improve the browsing speed and efficiency.
There are usually two types of proxy servers, Http proxy and Socks5 proxy. Http proxy is used to browse web pages, and its ports are generally 80 and 8080, but there are also other ports such as 3 128. Socks5 agent can be regarded as a universal agent, which can be used for telnet, ftp or irc chat. The port of this kind of proxy is usually 1080.