A proxy server is a network service that acts as an intermediary between a client and a target server, allowing the client to access network information and control the forwarded notification. The proxy server provides faster access, privacy protection by hiding IP addresses, and helps overcome access restrictions. It can be used for various purposes, such as connectivity, security, caching, content filtering, and access control. The proxy server operates at the dialog layer of the Open Systems Interconnection (OSI) model and acts as a security function provided by Internet link-level gateways. The browser sends a request to the proxy server, which then forwards the request to the target website, receiving the response and transmitting it back to the browser. The proxy server can cache web pages to improve browsing speed and provide functions such as security filtering, flow control, and user management. It can also be used as a network firewall to secure the intranet network and address IP address shortage issues.