The virtual world often uses this term for finding analogies from the real world. So, even in this case, "orphan" is the word for a child without his biological parents. An orphan website is a page, where no linking exists to other sites. The reasons are varied, it may be due to the unintentional removal of links or the no longer functioning links. Serious is the mistake, that a redirectioning was set up, which wasn't optimized for search engines, and therefore it is invisible to robots. Search engines recommend registering only the domain, not the subpages. However, this difficulty can easily cope with a sitemap, which takes ever site of the internet presence into its index. Since search engines cannot find the important links, an orphan page is, from the perspective of the search engine optimization, a relatively worthless page.