What is a Doorway Page?
Similar to a gateway page, a doorway page is a webpage created to rank for specific (majority of the time long-tailed) keywords while sending your users to a different page. It is one of the elements of black-hat SEO.
In Google’s eyes, doorway pages are classed as web spam as they provide no search value. Additionally, doorway pages can send users to malware or phishing websites. This is a key reason why Google implements regular algorithm updates to detect and diminish things like this!