TCP vs UDP: When to Choose Reliability or Low Latency (Quick Guide)

Quick primer for developers and ops: TCP vs UDP explained so you can pick the right transport for your app. Why it matters TCP = connection-oriented, reliable, ordered byte stream (retransmits, flow/congestion control). UDP = connectionless, message-oriented, low overhead and lower latency but no built-in reliability or ordering. When to use each (practical rules) Pick TCP when correctness matters: web (HTTP/HTTPS), file transfers, APIs, SSH, email. Pick UDP when low latency or real-time delivery matters and occasional loss is acceptable: VoIP, live video, online games, real-time telemetry. Consider hybrid options: DNS commonly uses UDP but falls back to TCP for larger responses; QUIC (modern HTTP/3) runs over UDP to combine low-latency with reliability. Common protocol & port examples TCP: HTTP (80), HTTPS (443), SSH (22), SMTP (25), FTP (21) UDP: DNS (53), SIP (5060), RTP (audio/video streams), many game servers (varies) Quick decision checklist Need ordered, guaranteed delivery? → T