The viewport is the visible area of a webpage on a specific device's screen, which varies by device size. Designing responsively for different viewports is a core requirement of mobile-first design.
Example
A page that fits a 1440 px desktop viewport also needs to work in a 390 px phone viewport without zooming or sideways scrolling.
Related resources
Glossary
Mobile-First Design
Mobile-first design means designing for the smallest screen first, then scaling up.
If your site takes more than 3 seconds to load on mobile, requires pinching to zoom, or has buttons too small to tap accurately, it's not mobile-friendly enough — and it's likely losing you both rankings and conversions. Over half of web traffic is mobile, and Google indexes your mobile version first. Test your actual site on a phone, not just a desktop preview. Small friction adds up fast on mobile.
How Do I Optimize My Website for AI Search Engines Like ChatGPT?
Write clear, self-contained answers to specific questions using structured formatting like headers and lists, build genuine topical authority around your subject area, and make sure your content is easy for AI crawlers to access and parse technically. AI tools like ChatGPT and Perplexity favor content that directly answers a question without requiring the reader to piece it together from a long article. This is the core of AEO, and it overlaps heavily with good traditional SEO practice.
