Please don't be offended right off the bat for the generic nature of this question :) Since I am rather new to AMP pages and have only been playing with AMP HTML so far - and it is inevitable to come across many digressions in tutorials or AMP docs themselves - I would like to ask someone here to nicely describe/define the purpose of using remote.html ...
Thank you in advance!
Remote.html feature is used by some AMP Pages to retrieve 1st- or 3rd-party targeting data. But from now on DoubleClick AMP Ad tags will ignore a feature called remote.html.
To continue retrieving this data and benefit from Fast Fetch, pages using remote.html you will have to switch to a new, Fast Fetch-compatible mechanism called “Real Time Config (RTC).” (https://github.com/ampproject/amphtml/blob/master/extensions/amp-a4a/rtc-documentation.md)
AMP Pages that do not use Real Time Config (RTC) and continue to reference remote.html after March 29, 2018, can still benefit from Fast Fetch. However; since remote.html will be ignored, those pages will no longer retrieve targeting data correctly. This may result in monetization impact.
Hope that helps!