1. A proxy configuration where the user's device has no knowledge that a proxy exists — the network infrastructure silently redirects all traffic to the proxy
2. A load balancer feature that maintains a persistent pool of pre-established connections to backend servers, eliminating per-request TCP handshake overhead
3. A load balancer feature that inspects request content and routes requests to specific backend server pools based on URL path or application-layer data
4. A publicly available, third-party-operated proxy used to bypass organizational security controls — can inject malicious content into traffic and capture user data