> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.ex2.com/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# What is the First Input Delay (FID)?

## The First Input Delay (FID) concept

The first input delay (FID) is a measure of the performance of a website. It represents the period between when a user interacts with your page and when the web browser responds to that interaction. 

This measurement can be taken from any element with which the user interacts for the first time. It is especially important on pages that users need to interact with, as it illustrates when the page becomes interactive.

The FID is one of [Google’s three Core Web Vitals](https://help.ex2.com/en/article/what-are-core-web-vitals-1uha3m2/?bust=1783450364656) settings, designed to measure the impact of loading times on the user experience of websites.

Core Vitals Web Base Settings also include two other settings: [Largest Contentful Paint](https://help.ex2.com/en/article/what-is-the-largest-contentful-paint-97c7e6/?bust=1784821730189) and [Cumulative Layout Shift](https://help.ex2.com/en/article/what-is-the-cumulative-layout-shift-cls-155a3y9/?bust=1784821730187).