Many sites base their designs on flash, javascript and plenty of images. They may please the eyes of the visitors, but the search engines can't understand these elements and because of that, such pages receive a very low ranking in most cases. If the webmaster wishes to receive any traffic at all from the search engines, he has three possible ways of correcting the problem.

The first way is to compromise by removing some of the design features that aren't appreciated by the search engines and adding things that the search engines can index. This means increasing the amount of plain text on the page and in some cases can also require a complete redesign of the site. Due to the time and money required to implement such changes and because the search engine friendly version might not look as beautiful as the old one, many webmasters aren't too keen on selecting this method.

The second way is to start cloaking. This solves the problem without having to change the content seen by visitors. Unfortunately cloaking requires quite a bit of effort from the webmaster as it needs continuous maintenance in addition to the work involved with setting up the system, so this solution also has its own problems.

The third way is to keep the old design and add external pages that are specifically designed to perform well in the search engines - doorway pages. This is probably the easiest and fastest solution and that is why it is, or at least has been, so popular among siteowners.