If you have never heard of Google's Accelerated Mobile Pages Project, it's exactly what it sounds like. AMP documents are minimal web pages, with the same basic HTML syntax, designed to load as quickly as possible (even at the cost of some functionality). Web developers can create AMP versions of their webpages, with Google mirroring every page on its own servers for the quickest load times possible. For example, here is the AMP version (left) and normal mobile site (right) from Forbes:

What you can't see is that the AMP page loaded in under a second, and the Forbes page took about 20 seconds. AMP pages have appeared to users for months in the 'Top Stories' section of Google search results, but starting today, the optimized pages will appear for all supported search results.

Websites that support AMP will have a small indicator (it looks like a lightning bolt), and Google claims they have served over 600 million unique AMP documents from sites like WikiHow, Reddit, Shopify, eBay, and others. Loading the accelerated pages is supported on the Google Search app for Android and iOS, as well as the Google web search on modern mobile browsers.

I personally am a massive fan of AMP, but my biggest issue is that navigating to the original page can be difficult. They often do not have all the abilities that normal websites have (for example, our Disqus comments would not work), so an easy way to get to the original page would be much appreciated.

This feature is rolling out gradually, so you may not see AMP results in search quite yet.

Source: Google Inside Search