TCP

TCP (Transmission Control Protocol) is the workhorse transport behind most internet traffic — web pages, email, file transfers. It establishes a connection with a three-way handshake, then guarantees that bytes arrive in order and without loss, retransmitting anything that goes missing. That reliability costs some overhead and latency: acknowledgements and retransmissions take time, and a single lost packet can hold up everything behind it (head-of-line blocking). Its counterpart UDP drops those guarantees for speed, which is why real-time apps often prefer it.

Because TCP is connection-oriented and universal, it is what most proxies relay. A SOCKS5 proxy forwards TCP (UDP needs support from both the client and proxy), and an HTTP proxy's CONNECT tunnel carries the TCP stream underneath HTTPS. TCP's reliability is why bulk transfers and page loads work predictably through a proxy, while its latency sensitivity is why an extra hop can noticeably lower throughput on high-latency links. When performance matters, measure a real transfer through your chosen path rather than assuming the proxy hop is free.

Because TCP is universal, it is the transport most proxies relay: SOCKS5 forwards it, and an HTTP proxy's CONNECT tunnel carries the TCP stream under HTTPS. Its reliability makes page loads and bulk transfers predictable through a hop, while its latency sensitivity means an extra hop can lower throughput on long links. When performance matters, measure a real transfer through your chosen path rather than assuming the s4m proxy hop is free.