Source: https://uptimeify.io/resources/platform-and-support/glossary/ttfb

# TTFB (Time To First Byte)

> Time To First Byte (TTFB) is the time between making a request and receiving the first byte of the response.

TTFB captures server-side latency: DNS resolution, connection setup, and how long the server takes to start sending a response. A high TTFB points at backend or network problems rather than front-end rendering.

It is a component of overall [response time](/resources/platform-and-support/glossary/response-time) and a useful diagnostic when a site feels slow before anything even appears on screen.