Viewport
The viewport is the user's visible area of a webpage on their device's screen. Its size and dimensions vary depending on the device (mobile phone, desktop, etc.). It is a fundamental concept for Responsive Design and for calculating key performance metrics like LCP and CLS, which are measured relative to the content within the viewport.
Related web performance terms
- Visually Complete
Visually Complete is a lab metric that marks the point in time when all the content in the visible, above the fold portion of the page has finished rendering.
- A/B Testing
A/B testing is a method of comparing two versions of a webpage to see which one performs better. For example, an e-commerce store might show 50% of its visitors a green "Buy Now" button (Version A)…
- AVIF
AVIF (AV1 Image File Format) is a modern, next-generation image format that provides significantly better compression than older formats like JPEG and WebP.
- Abandonment Rate
Abandonment Rate is a metric that measures the percentage of users who start a specific process (like a checkout funnel or a sign-up form) but leave before completing it.