What are backlinks? An overview

Before the emergence and growing relevance of search engines, website operators used hy­per­links primarily to make it easier for users to navigate the Internet. Nowadays, the find­ab­il­ity of websites on Google and other search engines is crucial to attract website visitors. Ac­cord­ingly, the im­port­ance of search engine op­tim­isa­tion (SEO for short) has grown steadily.

So-called ranking factors are decisive for the placement of websites in search results. They are subject to constant ad­just­ment and di­ver­si­fic­a­tion. With the emergence of search engines, backlinks have been important ranking factors, but their re­quire­ments have changed over time. This article reveals what backlinks are, how exactly they are struc­tured, and what their im­port­ance is for search engine op­tim­isa­tion.

The term ‘backlink’ describes a link that ori­gin­ates from one domain and leads to another. Hy­per­links like these allow users to navigate the Internet and reach new websites. The Google crawler reaches websites in the same way to then crawl them.

For search engines, existing backlinks are an in­dic­a­tion that a website and its content are relevant for readers. The more backlinks link to a site, the higher the prob­ab­il­ity that the site is popular and relevant. Google honours this by placing a site higher in its search results. The following sections explain how backlinks are struc­tured and how they are used as ranking factors in search engine op­tim­isa­tion.

Backlinks are usually not visible as links but via a so-called anchor text – the clickable words that link to a website. Most of the time, this text is high­lighted or un­der­lined in colour so that it is directly re­cog­nis­able as a link for a user. In the HTML source code, a backlink is struc­tured as follows:

The ab­bre­vi­ation ‘href’ stands for ‘Hypertext Reference’ and marks the URL to which the anchor text is linked. This source code can be expanded through various at­trib­utes. If you set a backlink to another site on your website, then it is advisable to add the addition target="_blank". As a result, the user does not leave their site, as the linked website opens in a new browser tab. The ad­di­tion­al attribute can be embedded in the source code as follows:

The so-called title tag is also optional. This allows you to define a text that appears in a box when you mouseover, thereby improving usability. In the source code, the title tag is specified as follows:

As of 2019 another attribute that can be used to mark backlinks set by users is the addition rel="ugc" which stands for ‘User Generated Content’ and signals Google that this link was not set by the website operators them­selves.

Backlinks are dis­tin­guish­able, among other things, because of their linked objects. We’ve already mentioned so-called text links – a word or several words with a link as anchor text. In a similar way, photos or graphics can also be linked to a website and used as a backlink. These enable a user to click on the image to go to a third-party website.

Another dif­fer­en­ti­ation relates to the effect of backlinks as a ranking factor. The HTML code displayed in the previous section is a so-called dofollow link. These backlinks act as important ranking factors for the search engine result. However, it is possible to exclude backlinks from being evaluated by the search engine. The required "nofollow" attribute can be in­teg­rated into the HTML code as follows:

A special type of nofollow link are backlinks in social networks, also known as social signals. These are usually auto­mat­ic­ally assigned the nofollow attribute.

In the early phases of search engine op­tim­isa­tion, the following principle applied: the more backlinks that link to a site, the more relevant it is for the user. As a result, linked sites often ranked higher in search results. Website operators took advantage of this by buying links or creating numerous websites them­selves to link to their own sites and improve their ranking. Google reacted and began to evaluate not only the number of backlinks, but also the sites they came from. Nowadays, the credo is quality before quantity.

In addition to their number, the value of backlinks has become a decisive factor to rank suc­cess­fully in search results. The value depends on various factors, but their exact weighting has not been revealed by search engine providers. Therefore, it’s advisable to pay attention to all factors and in­cor­por­ate only quality backlinks. The following para­met­ers influence the quality of a backlink:

• Relevance: Search engines evaluate whether linked sites are relevant for users. This is true if the linked and the linking websites deal with similar topics.
• Authority: Backlinks by trusted domains, i.e., trusted websites, tend to rank higher.
• Placement: A more prominent placement of a link results in more users clicking on them. Backlinks in sidebars, nav­ig­a­tion panes or footers are given less weight.
• Traffic: The more traffic the outbound site has, the more popular it is and the more mean­ing­ful its backlinks.

Link building is a sub­stan­tial component of an online marketing strategy and part of search engine op­tim­isa­tion. Below we introduce the three basic ways you can build backlinks. You can find more details on the topic in our dedicated article on ‘Building backlinks’.

The number of backlinks increases when other website owners link to your site. The more in­ter­est­ing and unique your website content, the higher the chances of these or­gan­ic­ally generated backlinks.

Some websites allow you to link to your own site. Typical examples are blogs with a comment section, forums, and business dir­ect­or­ies.

You can backlink by getting in contact with other website operators and asking them to link to your website. The following options provide a good value exchange for the webmaster and increase your chances of an active backlink:

• Replace broken links: Sometimes a website link to a site no longer exists. You can contact the site operator and suggest replacing the broken link with a new backlink to your site.
• Non-clickable links: Look for mentions of your website or your products that are not yet linked and ask the website operator to add a clickable link to their re­com­mend­a­tion.