An internal, inbound link points to a sub-page within a website, thus transferring the link power (so-called “link juice”) to the sub-page. At the same time, internal links also pass on the page rank (also called page rank flow). A page gets this link power from external inbound links. It is the homepage that has the most link power in most cases, hence making it the strongest page of a domain.
Internal linking is particularly important for the ranking of long-tail keywords, for which the respective sub-pages are optimized. Search engines go through the internal links to identify the structure of a website and then use this information to orient themselves. The internal linking can be compared to the layout of a city map. The crawler follows every link just like a new street in order to finally figure out the entire map. Through additional internal links, web operators can create virtual “abbreviations” both for the bot and visitors.
A rule of thumb for internal linking: The higher (stronger) the number of internal links pointing to a sub-page is, the higher its rank for its keywords will be. It is however important to note that a stringent internal linking alone is not a ranking criterion for Google or other search engines. What is rather more decisive is for the website to have a sufficient number of strong, external, inbound links.
Basically, there are two types of internal links. One is the structured navigation that transports the link juice hierarchically from top to bottom. The other is the horizontal linking between thematically relevant links.
With internal linking, it should however be ensured that the number of internal links does not exceed a certain limit. It is often said that every sub-page on a website should have no more than 100 internal links. This limit is however relative and depends on the strength of the page pointing to the subpage, i.e. the quality and strength of its backlinks.
Incoming internal links not only control the ink juice but also help the user to discover the deeper levels of a website. They guide users to helpful, additional information. Thus, webmasters have the possibility to use internal links to direct users to other content or products on an online shop.
Internal links help control the ranking for the respective keywords. Here, it also depends on the use of the respective anchor text. It is therefore advisable that one uses the same keyword on the same landing page in order to specifically use the link juice to push up the sub-page.
It is recommended to adhere to the rule of “one keyword (or keyword combination) per page”. However, in some cases, such as less competitive keywords, a sub-page can also be ranked highly for several “main keywords”. The nofollow & noindex, noindex & follow meta data can also be used to prevent bots from crawling some of the internal links or not to index certain content.
If a page does not have any inbound links, it is referred to as an orphaned page. It is advisable to edit such pages for the sake of the link juice and for a good page architecture.