Definition
A proxy server is an intermediary that accepts requests from a client and forwards them to other servers. Common types include HTTP proxies (handle web traffic), SOCKS proxies (handle arbitrary TCP and sometimes UDP connections), and transparent proxies (intercept and forward without explicit client configuration). Proxies are commonly used to filter content, cache responses, log activity, or appear to come from a different IP.
Proxy vs VPN
Two important differences. First, layer of operation: a proxy works at the application layer, so only configured applications use it (e.g., your browser); a VPN works at the network layer, so all device traffic goes through it. Second, encryption: most proxies do not encrypt traffic at all, only forwarding it; VPNs always encrypt the tunnel between client and server. A SOCKS5 proxy with HTTPS to the destination provides similar protection to a VPN against the local network but offers no protection against the proxy operator.
Use Cases
Proxies are useful when you need to change just one application's apparent IP (a browser-only proxy is lighter than a system VPN), when you need to chain multiple intermediaries, or when working in environments where a full VPN cannot be installed. Smart DNS services are a special case of proxying — only DNS and a few key endpoints are proxied, leaving the rest of traffic direct. For comprehensive privacy, a VPN is the stronger tool.