Getting backlinks (also known as external links), to your website from other sites is still one of the most effective ways to improve search engine rankings.
But not all backlinks are valued equally.
A handful of high-quality backlinks can significantly improve your SEO progress. At the same time, dozens of low-quality links can make little difference, or even have a negative effect if they’re considered spammy.
The Three Levels of Backlinks
In Google’s eyes, there are three levels of backlinks: low-quality, medium-quality, and high-quality.
Strictly speaking, Google classifies low-quality backlinks as web-spam. These are backlinks that have been created in a fake way to game the system, and they are against Google’s guidelines.
Medium-quality backlinks offer value and are easier to attain than high-quality links. High-quality backlinks provide the most value but are harder to achieve because often, the editorial standards are much higher.
The Three Core Elements of High-Quality Backlinks
What makes a high-quality backlink is subjective. Nobody knows for sure how search engines measure them, but most SEOs agree on three core elements.
Backlinks should be natural and where the website owner chooses to link to your site because it provides value to their readers and NOT because you paid them to do so or tried to manipulate them in another way.
This natural approach is an example of ‘earning’ a backlink.
This differs from unnatural backlinks where the intent is usually to fool search engines into believing that a website has a better reputation than it really does.
If Google believes a backlink is unnatural or spammy, Google may at first ignore it, and for repeat offences, punish the site and demote them in its search engine results.
In addition to being natural, backlinks should be reputable.
Modern search engines look for social proof in how credible webpages are. Google has its dedicated PageRank algorithm which measures the importance and reputation of webpages. Here’s Google definition:
PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.
So, the higher the number, more importantly, the higher quality of backlinks a webpage gets, and in turn the higher its chance of ranking for competitive keywords.
Google used to provide a metric for PageRank, and this calculated a rough estimate of the reputation of a webpage. Google stopped this because spammers were using it as a currency to buy backlinks which is against Google’s guidelines.
So, think of PageRank as an algorithm or concept and not as a metric.
The Rel Link Attribute
Now, while we talk about search engine reputation, I want to cover the ‘rel attribute’, and this can be added to an HTML link.
By default, regular HTML links don’t have the rel attribute, and this means that search engines can pass PageRank, from one page to another.
However, HTML links that contain values in the rel attribute often don’t pass search engine reputation, or at least not the full amount possible.
These include the ‘sponsored’ rel attribute, the ‘UGC’ (user-generated content) rel attribute, and the ‘no follow’ rel attribute.