AMP is a very lightweight version of a webpage that has been stripped of the many elements that cause a regular webpage to display slowly, such as tons of cookies, third-party Javascript, and slow-loading ad networks. This results in a page that loads lightning-fast, which is great for those who are on slower connections or simply don't want to wait for a regular, heavier page to load.
AMP has had a fairly positive reception both from site owners and from users. It's much faster and more streamlined for searchers, especially on mobile devices that tend to be a little bit slower connection-wise.
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