Doorway Pages Blackhat Seo Technique
Doorway pages are called as Gateway or Bridge pages.These are custom pages created with a set of keywords that will be shown to the search engines to redirect traffic.
If a website like http://www.pqr56.com/ is gateway pages optimized with keywords "pqr56", this webpage will be visible to visitors when they search for the keywords, but clicked on the links they will be redirected to the original web page. But the search engine spiders may index these doorway pages for the same keywords present in the original webpage.
Most of them are created independent of the original website. Bridge pages are created using automated software, and then these are submitted to search engines individually. This is obviously a blackhat SEO technique that should not be followed.
These pages are tracked by the search engine spiders very easily. The links of these pages are not submitted in other sites, but this page has links to a specific website.
Search Engine vs. Doorway pages:
In the earlier years, search engines were not able to find out bridge pages. Now major search engines and directories don't recommend black hat SEO technique. Search engine spiders also follow many other techniques to crack down on these doorway pages. First they check for the navigation path, the redirection methods used and so many other factors to find "gateway pages". These pages are just like clicking on advertisements to go to concerned web page. There are clear guidelines to avoid usage of bridge pages. Google clearly bans website using this technique.
It would be a better idea to have a hold on the urge to get more traffic within a short span of time. Following this black hat SEO technique of "Gateway pages" may end up in your website being penalized.