TTFB (Time To First Byte) is a server performance metric that measures the time it takes for a user's browser to receive the first byte of data from a web server after making a request. It is an important metric to assess the responsiveness and efficiency of a server in delivering content.
When a user visits a website, their browser sends a request to the server for the requested web page. The server then processes the request, gathers the necessary data, and generates a response. TTFB specifically measures the time it takes for the server to start sending the first byte of this response back to the user's browser.
The TTFB duration includes the time it takes for the request to reach the server, the server's processing time, and the time it takes for the first byte of the response to travel back to the user's browser. It does not include the time it takes for the complete response to be delivered or rendered by the browser.
A low TTFB generally indicates a faster and more efficient server response, while a high TTFB can indicate potential server performance issues or network delays. Factors that can affect TTFB include server processing power, network latency, server load, caching mechanisms, and the complexity of the requested content.