The term backlink (also: inbound link) in SEO refers to an external link from another domain to your own website. A backlink thus is a reference from one website to another and signals a certain trust in the linked page.
Links between different web pages are the core of the World Wide Web. Only through links networks are created which constitute the essence of the internet. Search engines need these connections between web pages to find and index information because the crawlers of search engines follow links to move through the web. Links are therefore not only the foundation of the internet but are also specifically relevant for search engine optimization (SEO).
Backlinks play a special role in SEO because they enable search engines to determine which websites are more frequently referenced for a certain topic and are therefore relevant for it. Besides the optimization of your website itself (= on-page SEO), you should, therefore, ensure that you are referenced on other websites through link building (= off-page SEO) since backlinks can be seen as a recommendation for your site and are one of the most important SEO ranking factors. The higher the number of backlinks, the higher the link equity and relevance of your website, because with each backlink, some link equity is passed on to your site. The term link equity refers to all positive properties of a link that are passed on to the linked page.
However, not every link has the same effect on SEO. For example, backlinks pointing to your home page/domain only increase the general authority of your website. On the other hand, links pointing to specific subpages/contents can directly improve your ranking for the topic dealt with on that page. However, this requires a thematic coherence between the linked pages, because a link between completely different contents will only slightly increase the importance of your website.
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Basically, Google attaches much more importance to the quality of your backlinks than to their number. The reason for this is that Google wants to counteract the purchase and sale of links and ensure the significance and trustworthiness of backlinks. But what makes a backlink one that can improve the quality of your backlink profile and thus your SEO strategy?
First of all, your backlinks should come from trustworthy and reputable websites. These are websites of universities, public institutions, etc., which have a high domain trust and thus also increase the trustworthiness of your own site. In contrast, backlinks from bad neighborhoods (e.g. spam pages that are only used to generate backlinks) can have a negative effect on the trustworthiness of your site and in the worst case even lead to an exclusion from the Google index.
Furthermore, backlinks should come from thematically relevant websites, since a thematic connection between the linked pages makes a backlink more relevant and thus leads to a more positive rating of your site by Google.
In addition, credible backlinks tend to come from the same country, industry, etc., because this seems much more plausible for Google than links to your site from distant countries that seem to have no connection to your website. For example, if an online shop for sports equipment based in Germany suddenly receives a backlink from an electronics manufacturer in India, Google will find this very unnatural. As a result, Google could conclude that the backlink was acquired illegally.
Another important characteristic of a good backlink is an appropriate anchor text, which contains the most important keywords for your web page. This helps to improve the ranking of your page for corresponding search queries. However, backlinks with exact-match anchor texts are often difficult to achieve, as companies are usually linked with their name and not with the search terms that are relevant for them. In addition, too many exact-match anchor texts appear unnatural and may be classified as spam.
Concerning anchor-texts, you should also make sure that they match the actual content of your page. Otherwise, they could also appear unnatural and be interpreted as spam. For example, if a blog article about a newly published book contains a link with the anchor text "credit without background check", this not only of no use for readers of the article, but also appears rather unnatural to Google and is therefore rated negatively.
In addition, you should try to have more follow than nofollow backlinks. Nofollow links do not transmit any link equity to your site and thus have less influence on the ranking of your web page than would be the case for follow links.
Last but not least, you should also take into account the recency of your backlinks. Regularly added new backlinks indicate that your site provides users with up-to-date content, which is rated positively by Google.
In summary, you backlinks should have the following characteristics in order to be evaluated positively by Google:
- trustworthy and reputable source
- thematic coherence between linked pages
- come from the same country, industry, etc.
- keywords in anchor text
- anchor text that relates to the actual content of the linked page
- more follow than nofollow links
Link building is an extremely important task in the context of search engine optimization (SEO), however, not every link is equally valuable. Therefore, we will explain both good and bad options for link building in the next section and give some general recommendations at the end.
The most natural approach to link building is to create valuable and unique content for users in order to get attractive for links from other sites. With this organic link building through content marketing, you provide visitors to your website with added value that they voluntarily link to. Since Google also advocates this method, it is the best tactic even though it’s not the easiest one.
Another approach is so-called "link baiting", where bait is laid out to tempt other websites to link to your page. This can take the form of an infographic which is sent to relevant pages with the aim of generating backlinks for your website.
A quite simple tactic for companies would be to ask customers or suppliers whether they could link to the company website under references or similar. However, you should choose only trustworthy business partners for this.
In addition, you can link your website in your social profiles on Facebook or Xing as well as add it to thematically relevant and high-quality directories and yellow pages.
In addition, you can search for potential thematically relevant link sources or pages that link to competing websites. In the next step, you could contact them and offer them a guest commentary, for example. In addition, it is also possible to search for mentions of your site where no link has been set. For this purpose, you can use Google Alerts where you get a notification each time your website is mentioned somewhere on the web.
Another recommendable link building tactic would be to link to high-quality and thematically relevant pages yourself and to inform the owners of those sites about it so that these become aware of your website and possibly link back to it.
For more link building tactics, check out this blog post.
Besides the link building tactics listed above, you can often observe link building practices on the web that are less recommendable.
These include registering your website in all existing web directories or spamming blog comments with links to your site. Such spam can quickly backfire in the context of SEO.
Also avoid the purchase of links on special platforms or by directly contacting the owners of other websites, as this violates search engine guidelines. There’s a similar problem with link exchange: Google does not like it and therefore you should only use it to a limited extent. Links between sites without thematic coherence only have a small positive influence on your ranking anyways.
Generally, and regardless of the tactic you choose for link building, your SEO strategy should always be based on white-hat link building. This means that you shouldn't add lots of links in a short period of time and then suddenly stop because Google might punish your website if the number of backlinks is increasing too quickly. In addition, try achieving a balance between different kinds of backlinks, because there certainly is no website that only gets follow backlinks from trusted and reputed sites. Instead, it seems much more natural if your page gets backlinks from unknown pages or nofollow links in addition to such links.
Backlinks are among the most important ranking factors and link building is, therefore, a topic you definitely have to deal with sooner or later in the context of SEO. For this task, you will have to get creative, both with regard to creating interesting content and to convincing potential link sources. Although there are other possibilities for link building that require much less effort, you should remember that what works easiest usually is not what brings the greatest benefits to your website.