Hello,
Webmasters are sometimes told to submit “bridge” pages or “doorway” pages to search engines to improve their traffic. Doorway pages are created to do well for particular phrases. They are also known as portal pages, jump pages, gateway pages, entry pages, and by other names as well.
Doorway pages are easy to identify in that they have been designed primarily for search engines, not for human beings. This page explains how these pages are delivered technically, and some of the problems they pose.
Doorway pages are pages that are designed specifically for ranking benefits. They consider search engines, but not users.
So there are a number of types of doorway pages. Two commonly seen are cloaking and redirection pages. These are pages designed for search engines to see, but users don’t see these pages. If you click on one of these pages in the SERPs, you’re instantly redirected to a more useful page.
Content rich doorway pages, these have had design slightly in mind, but again the information on those pages aren’t actually useful and they require you to take an extra step to find the information that you’ve actually searched for in Google.