What Does Responsiveness or Mobile Friendly Mean ?
There are more number of mobile devices than the number of people in the world. Google soon is going to have a separate index for mobile which will be a primary one.
Ensuring a good mobile experience for the online visitor is much more than just making the website display correctly on various device screens.
Mobile Friendliness or Responsiveness
Mobile-friendly pages are pages with Responsive Web Design (RWD). RWD is a web design approach aimed at crafting sites to provide an optimal viewing experience across a wide range of devices -from desktop computer monitors, tablets to mobile phones. In particular, reacting to the width of the browser window — not just flowing the text, but often changing aspects of page layout.
Accelerated Mobile Pages & Progressive Web Apps
Accelerated Mobile Pages (AMP) are lightweight pages designed to load quickly on mobile devices. AMPs are served from the Google AMP Cache, which is a proxy-based content delivery network for delivering all valid AMP documents. It fetches AMP HTML pages, caches them, and improves page performance automatically.
AMP can ensure instant page load but cannot retain the same performance in case of complex functions like online payments and other dynamic functionality. That is where Progressive Web Apps (PWA) come to the rescue.