A link hub is a website that links to several different pages, but these are all related to a particular topic.
A link hub is based on the assumption that not all links are rated equally by Google. It is a website that is considered to be a kind of “expert” by Google. The link hub is linked to various sites on a particular topic. This shows that the site operator understands something about his subject, because he knows the most important topic-related websites. Google recognizes this added value and rates backlinks that originate from such link hubs particularly high. Accordingly, link hubs are a popular method for link building.
A link hub can happen by accident or intentionally. Link hubs arise on private websites by accident. Suppose a terrarium fan links to a list of major online retailers, other private sites on the topic, as well as information and definitions in Wikipedia. Google realizes that someone has deliberately selected information that could be of interest for its readers and rates them accordingly higher.
Link hubs may also arise through link buying or renting. Suppose an online retailer discovers this little private terrarium website that previously linked only to non-commercial information services. They buy or rent a link from that website and will henceforth be listed on the link list or the blogroll. Other online retailers and traders recognize that retailer no. 1 is listed there and also book a link. Within a short time, a list is created of the seemingly most important dealers. The original website, turned into a link hub. Since this did not happen naturally, there is a risk that this link buying practice will sooner or later be noticed and the link hub and backlinks will be completely devalued.
However, link hubs can also be deliberately built up with the aim of passing the entire link power and trust to another website, which is the actual target of the links. Search engine optimizers would accomplish this as follows. A website gets built with a small amount of content and links from there to other topic-relevant webpages. This may even include links to the competition, since the link hub will then seem “genuine.” To strengthen the link power of the link hubs itself, a bit of link building is now undertaken for this website. Sometimes methods are used for this purpose which do not comply with Google Webmaster Guidelines, such as link exchanging, buying or renting. Once Google has recognized the site as a link hub, it will pass its link power to the linked pages.
Even the best link hub can be devalued if the site operator suddenly starts including a variety of links that are not topic-relevant. If the terrariums website now links to websites with the topics of car insurance comparison, betting, loans or cribs, etc., Google will recognize a pattern that is already known from other websites. These are indiscriminate link exchange or paid links. Since neither fulfills the purposes of the Webmaster Guidelines, the link hub sooner or later loses its meaning and hence its special status in terms of better evaluation of outbound links.
A link hub within a website, is a subpage that is particularly well linked externally. These are often caused by link baits due the viral spread in social media or the very timely address of a current topic. Such internal link hubs can be used to redirect link power to weaker subpages of a website. For this purpose, you have to link from the specific article to the subpage in question.
Genuine link hubs are a gold mine for SEOs because they can produce very important links with relatively little effort. Thus link hubs are an important part of a link building strategy.
For search engine optimizers, the challenge is to discover expert webpages which already link to multiple competitors but not yet one’s own website. With such sites the focus of attention should be on being listed as well, to benefit from the same trust as the competition websites. Hub finders exist, since such expert pages are not easy to track down. These are partially available for free, but are often also part of the big SEO suites. You can enter the websites of your competitors and search for websites that link to all or some of them. This is a strong indication for the presence of a link hub.
Before you decide to get your own site listed there, however, you should always check first whether that website actually has high authority or whether it is nothing more than an inferior link exchange site.