Proxy server

A server that relays requests between clients and other servers. It can mediate access, filter traffic, cache responses, or conceal a client's network address.

Forward proxy: A proxy that forwards requests from clients to external servers on their behalf. It represents the client side of the proxy-server model.
Web cache: A store of previously retrieved web resources that can satisfy later requests without fetching them again. Caching lets a proxy reduce repeated network transfers and response time.
Client–server model: A computing architecture in which clients request services and servers provide them. A proxy occupies an intermediary position between the two roles.
Network address translation: A technique that modifies IP address information in packet headers as traffic crosses a network boundary. NAT changes packet addresses, while a proxy terminates and relays application or transport connections.
Reverse proxy: A proxy that receives requests for one or more servers and forwards them to backend servers. It represents the server-facing arrangement, often hiding backend infrastructure.
Content filtering: The examination of data or requests to allow, block, or modify content according to rules. A proxy can enforce filtering policies on traffic passing through it.
Internet Protocol: The network-layer protocol suite that routes datagrams between hosts across interconnected networks. Proxies depend on IP routing to communicate with clients and destination servers.
Gateway: A system that connects networks or protocols and can translate traffic between them. A gateway may route or translate traffic without acting as a request-relaying proxy.
HTTP proxy: A proxy that handles HTTP traffic, forwarding requests and responses between clients and servers. It shows how proxies can specialize in a particular application protocol.
Load balancing: The distribution of incoming work across multiple computing resources. Reverse proxies commonly distribute requests among backend servers.

Linked from 3 pages

Tunneling protocolCompared with: A proxy terminates and relays a connection; a tunnel typically transports encapsulated packets between endpoints.