Field Data (Real User Monitoring - RUM)
Field data is performance data collected from the real users visiting your website in their actual environments. It captures the true user experience across the full spectrum of devices, network conditions, and geographic locations. It is often called Real User Monitoring (RUM). Unlike Lab Data, which is simulated, field data is the source of truth for how your website performs for your actual audience and is what Google uses for its Core Web Vitals ranking signal.
Related web performance terms
- Fail-safe Mechanism
A fail-safe mechanism is a core architectural principle of Speed Kit that guarantees the service will never slow down a website.
- Fetch Priority (`fetchpriority="high"`)
The fetchpriority="high" attribute is an HTML attribute that tells the browser to prioritize loading a specific resource (like an image or script) higher than other resources of the same type.
- First Contentful Paint (FCP)
First Contentful Paint (FCP) is a performance metric that measures the time from when a user initiates loading the page until the first piece of content (text, image, or other element) is rendered on the screen.
- Flash of Original Content (FOOC)
See Flicker Effect.