Definition

TTFB

TTFB, or Time to First Byte, measures how long it takes from making a request to receiving the first byte of the response. It reflects DNS lookup, connection, and server processing time, and a high TTFB drags down perceived speed and Core Web Vitals.

Related terms

Latency

The delay between a request being sent and a response beginning.

Core Web Vitals

Google's set of metrics for loading, interactivity, and visual stability.

DNS

The system that translates domain names into IP addresses.

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