For a long time search experts and content marketers have understood that search engines use the number and variety of backlinks to a page as a quality signal that has an impact on rankings. 

So how important are they now?

In Searchmetrics’ annual study of the characteristics of pages with a high Google ranking and the key factors that correlate with (or are more likely to appear on) these pages, we found that relevant, quality content is now more important than ever.

But what about backlinks? The logic goes that if a lot of other websites point to a page, then it must be valuable and useful.

This is why backlinks have been one of the important factors used by search engines to determine organic rankings.

And this is also why attracting backlinks has been a core part of the strategy used by content marketers and SEOs to help their content rank highly.

In our study, which is based on an analysis of the top 30 search results on Google.com for 10,000 relevant keywords, we found that while backlink features still show a fairly high correlation with rankings, their value is gradually declining.

This isn’t too surprising since Google has tried to clamp down on those who try to game the system by building false (or unnatural) links just for the sake of improving rankings.

Here are five key findings from our study when it comes to backlinks:

1. Number of backlinks

The correlation between the number of backlinks that pages have and their ranking positions is 0.28.

This is still fairly high, but it has been declining since 2013. And we expect this trend to continue.

Overall, while pages in the top 30 search results tend to have significantly more links than in previous years – the gap between those in the top position and the rest is narrowing.

2. Referring domains

The number of different referring domains (i.e. the different sites where backlinks are coming from) was higher for the top 30 search results in 2015.

This trend is particularly true of large brands as they occupy the top ranking positions and it is here that the growth of referring domains is most clearly visible.

This makes sense because in general you would assume that a site that has links from a large number of separate sources is more popular (and more likely to be genuinely useful) than a site that has the same number of links from far fewer separate sources.

Indeed, if all the links came from one or two sources it begins to look a little suspicious and unnatural – perhaps there is some sort of paid linking scheme or an agreement to provide links.

Alternatively it may be a sitewide link, located in the sidebar or footer of every page – however in this case Google simply counts this as a single link, and one that is generally even less valuable than a relevant and topic-related link from the core content of a page.

3. Backlinks with keyword in anchor text

The proportion of hard backlinks, which include the keyword in the anchor text, is falling, and this is part of a longer term trend.

In 2014 29% of backlinks had the keyword in the anchor text – this year it had shrunk to 26% on average (see chart).

Of course it is natural or normal to have some, but not large numbers of links with a target keyword in the anchor text pointing to a page, for example ‘cheap car insurance’ on a page that offers this.

So the declining proportion of this factor is another consequence of Google’s attempts to prevent link building specialists artificially creating links to boost search rankings.

4. Domain name in anchor text

The percentage of links with the complete domain name in the anchor text is increasing, from 7% to 10% over the last year.

This is because Google realizes that it’s natural for people to use the brand name or URL (e.g. Tesco, Asda.com) when linking to other pages (in particularly, it’s much more natural than links with specific target keywords).

5. Backlinks from news sites

The number of backlinks from news sites to homepages that feature in the top search results is growing. For example, in the top 10 search results the number of backlinks from news sites increased from 333 in 2014 to 522 in 2015.

It seems that Google recognises that the links from news sites are a reliable indicator of quality (it is harder to manufacture false links from online publications) and content freshness.

The declining importance of backlinks

As the Searchmetrics Ranking Factors study has shown, backlinks are still important – but overall their value is falling and we expect this trend to continue.

Certainly, the era of using link-building as a shortcut to help your content rank higher is coming to an end.

The future is all about creating genuinely useful and valuable content that other sites are happy to link to in order to help their readers access further related information.

In other words, link earning, rather than link building is how you’ll climb up the rankings moving forward.

About the data:

The Searchmetrics Search Ranking Factors and Rank Correlations – Google US 2015 study analysed the top 30 search results for 10,000 relevant keywords, which adds up to approximately 300,000 websites appearing on Google.com.