You go to a site that you’ve enjoyed and bookmarked sometime in the past but haven’t visited in a while, and it’s changed. The topics it discusses are different, or the writing style isn’t quite the same, or it suddenly has links within its content to commercial pages that it probably wouldn’t have linked to before, or all of those things. It also seems heavily focused upon more commercial terms and content. It’s changed, and now its pages now have the appearance of what many might call “doorway pages.”
Doorway pages have also been referred to by terms like gateway pages, entry pages, bridge pagers, portal pages, and their primary purpose is to attract visitors from search engines in order to send them to other places.
As a site owner, you don’t want Google to start identifying your pages as doorway pages. Google’s Webmaster Guidelines tell us to: