Make the network between server and client fast — cutting round trips rather than bytes, connection reuse and TLS handshake cost, choosing between HTTP/1.1, HTTP/2 and HTTP/3, picking polling versus SSE versus WebSocket, and why mobile radios make small frequent requests disproportionately expensive. Use when optimizing page load or API latency, configuring an HTTP client or server, choosing a realtime transport, or diagnosing why something is slow despite adequate bandwidth.
