In our Introduction to Search Engine Optimization, we outlined how valuable links from other websites to yours ("backlinks") are in allowing search engines to determine how important your website is for any given search term. No matter how well made your website is, and no matter how high the quality of your website's content is, you will not benefit from high search engine rankings without high quality backlinks.
High quality backlinks help search engines to define your website as an authority on a subject. Given two websites of similar structure and quality, the website with the most high quality backlinks will nearly always be ranked higher by the major search engines. Having lots of high quality backlinks to your website will therefore have the dual effect of increasing traffic from search engines and increasing traffic coming from people following links to your website.
Since Google and other search engines use backlinks as one of the ways to determine how important each website is, it is important to them that this is an accurate way of doing so. If Google simply ranked the websites with the most backlinks as being most important it would not be able to produce high quality search results. Therefore, every backlink has the potential to either be valuable, fairly inconsequential, or even harmful to your website's search engine rankings.
In the last six to twelve months, Google has begun to fight back against some so-called "black-hat" SEO methods (see Search Engine Optimization Methods You Must Avoid), with many websites being punished for engaging in the generation of artificial backlinks. The result is that your search engine rankings will be harmed (and in some cases actually removed) if websites featuring these links also link to your website, since this earmarks your website as engaging in unfair practises. However, website owners are able to take "manual actions" to have these links discounted via their Google Search Console (formerly Google Webmaster Tools) account.
Google has also been actively discouraging backlinks that are paid for, and has punished some major websites for using this practise. "Google tends to look at buying and selling links ... as a violation of our guidelines", said Matt Cutts, head of the Webspam team at Google. Even though it is unlikely that Google is able to automatically detect such behavior, and that it was probably just making an example of some websites, it is worth avoiding any method that Google's guidelines discourage.
The increasingly sophisticated nature of Google and Bing's algorithms has probably resulted in most backlinks falling into this category of link. Some examples of backlinks that are of little value to search engine rankings are as follows:
High quality backlinks are of such value that it is better to have only a few of these than many low quality backlinks. Some examples of backlinks that are of high value to search engine rankings are as follows:
Google periodically updates it's search algorithms, which dictate how highly ranked websites are, and there have been some signs recently that Google's algorithms are attaching less significance to backlinks. The "Panda" and "Penguin" algorithm updates punished many websites that contained duplicate content or content that was machine-generated, signifying that high quality, original content was being considered as being more important than ever. This, coupled with Google's long-term quest to provide more accurate search results using "natural language" queries (i.e. conversational phrases), has raised fears among the SEO community that backlinks will cease to be important.
However, Google has admitted that there is no good alternative to using backlinks as the most important ranking factor, at least for the next few years. "Well, I think backlinks still have many, many years left in them. But for the most part, people care about the quality of the content on that particular page. So I think over time, backlinks will become a little less important.", said Matt Cutts, head of the Webspam team at Google.
Last updated: 4th June, 2014