Mobile-first web design means designing the mobile experience first and expanding to larger screens - the reverse of the historical desktop-first approach. It matters critically for Indian businesses because over 70% of Indian internet traffic comes from smartphones, often on varied 4G speeds. A mobile-first approach ensures fast load times, thumb-friendly navigation, appropriately sized text, and content hierarchy that works on small screens without horizontal scrolling. Google uses mobile-first indexing, meaning the mobile version of your site determines your search rankings. A mobile-first website also dramatically improves the performance of performance marketing campaigns - paid traffic converting on mobile converts at significantly higher rates on a mobile-first site.