Technical Definition of Response Time
Response time is the total duration in milliseconds required for a web client to execute a network request and receive the complete response payload from a target server. It is a key metric in web performance auditing, directly impacting visitor experience, conversion rates, and SEO rankings.
Response time is not a single variable. It is the sum of several distinct network and server processing stages:
- DNS Resolution: The time required to resolve the hostname to an IP address.
- TCP Handshake: The time taken to establish a connection between client and server.
- TLS Handshake: The time required to negotiate SSL/TLS encryption.
- Time To First Byte (TTFB): The time the server takes to process the request and send the first byte of data.
- Content Transfer: The time required to stream the remaining response payload back to the client.