Persistent HTTP Connection

networking http

Definition

Persistent HTTP Connection

A persistent HTTP connection (also called HTTP keep-alive) is a single TCP connection that remains open across multiple HTTP request-response pairs, instead of being closed after each exchange.

In 1.0, connections are non-persistent by default: the client opens a new TCP connection for every request. 1.1 makes connections persistent by default, controlled by the Connection: keep-alive and Connection: close headers.

Reusing a connection avoids the overhead of repeated TCP handshakes and slow-start, reducing latency for pages that require many resources.