The 3 Core Web Vitals are a set of 3 metrics to measure the user experience of a web page.

1. Largest Contentful Paint (LCP)
2. First Input Delay (FID)
3. Cumulative Layout Shift (CLS)

Largest Contentful Paint (LCP):  The LCP will assess how fast the main content of a web page is loaded. The LCP will measure the time from when the user initiates loading the page until the largest image and or text block is displayed within the viewport.

First Input Delay (FID): In a nutshell, The FID will measure the timing and the speed of your website.  This metric measures the time from when a user first interact with your website to the time the browser is actually able to respond to that interaction.

Cumulative Layout Shift (CLS): The CLS us a metric measuring how often a web page will unexpectedly shift during its lifespan.