In the question and answer portion of the 10/1/2021 John Mueller hangout, one webmaster asked him about doorway pages.
Basically, the webmaster has a single page that leads users who are searching for the non-scientific name for a cactus to the original page itself.
John explained that they would call anything a doorway page if it leads users to the exact same marketing funnel after it’s clicked on.
You’re basically taking many different keywords and guiding users to exactly the same content at the end of that journey.
He provided an example where this would not be a doorway page—in an encyclopedia. There is very unique content at the end of that funnel.
He also explained that one technique for creating doorway pages that Google doesn’t like is a common local SEO technique where one page of content leads to the same content on many different location pages.
He likened this to creating many different doorways that lead to exactly the same house.
This discussion happens at approximately the 35:35 mark in the video.