Doorway pages are HTML documents that have only one aim: to rank higher at search engines for one or more keywords and thus to attract more visitors to your website.
Normally, doorway pages consist of lots of text and only few design elements. The text of doorway pages is not meant to inform visitors, but it is directed to search engines. It is meant to cheat search engines and to pretend that a document (it is to say the doorway page) is especially relevant for specific keywords.
That is why the text of a doorway page often consists of incoherent text or unnecessary word repetitions of specific terms.
Therefore, doorway pages are never linked from a website. Only the doorway page links to the website. You can reach a website via doorway pages, but if you are on a website, there is no link back to the doorway page.
In the following, you learn why doorway pages sometimes cause problems and how you solve these problems.