The problem: there’s a lot of information out there about link building. Some of it good. Some of it not so good. Some of it just plain bad.
So to help you build links the right way, we’ve put together this complete, noob friendly, guide to link building.
We’ll be covering:
- link building theory
- essential skills and tactics
- the best link building tools
- linking to some of the best link building tutorials and case studies on the web
We’ll also be revealing the results of our recent industry wide link building survey.
But let’s start with the basics.
Link building is the process of acquiring new inbound links (backlinks) to a website from external sites.
The goal of most link building campaigns will be to increase future search traffic from Google, although links from popular sites (such as newspapers) can also be an excellent source of referral traffic.
Our own research has found that link popularity (the number of inbound links to a site/page) continues to have a high correlation with Google rankings.
Indeed, the chart below (taken from our study of over 2 million keywords) shows that link signals have a much higher correlation score than individual on-page factors (meta tags, keyword usage etc).
In simple terms, each link to a website is considered as a vote. The more votes a site accumulates, the more likely it will be to show up for a particular search query.
However it is not a ‘one member, one vote’ system.
There are a number of factors which determine the weight Google will assign to a particular link and how likely it will be to influence future rankings. These include:
1.1 Authority Of The Linking Page/Site
As a site accumulates links its own authority increases. It is then able to pass on more authority (votes) when it links out.
So a link from a high authority site (such as the BBC) will generally be more powerful than a link from a low authority site (for example a new site with no inbound links of its own).
Ahrefs has 2 metrics which can help you determine the authority of a linking page or site:
- Domain Rating (DR) — refers to the overall strength (authority) of a site and is measured from 0–100 — with 0 being no authority (for example a new site with no inbound links) and 100 being the highest.
- URL Rating (UR) — refers to the strength (authority) of an individual page and is measured from 0–100.
In the example below, we can see that this page has a DR score of 67 and a UR score of 32.
We can also see that Ahrefs has discovered 66 domains linking to this page. These are the links which have contributed directly to the UR score.
Ahrefs is well known for its huge index of backlinks, so you can rely on our metrics when assessing the authority of a website or page.
Recommended Reading: Ahrefs’ SEO Metrics Explained (Finally).
1.2 NoFollow Links
Certain links (for example links from blog comments) may have the rel=”nofollow” attribute applied.
To comply with Google’s guidelines, any paid links should also have the rel=”nofollow” attribute.
The nofollow attribute instructs search engines not to follow the link and in theory links with this attribute should not contribute to rankings.
Opinion varies however on whether this is actually the case.
For example, links from wikipedia are nofollow and many leading SEOs consider wikipedia links to be beneficial for rankings due to the site’s high trust (see this article for more).
We asked link building expert Eric Ward for his opinion on whether nofollow links contribute to rankings:
I believe that any search engine with the goal of returning accurate results must maintain ultimate control over what it does and does not give credit to, and selectively choose the signals it values. And this includes rel=nofollow. I think it is perfectly reasonable to assume that any search engine can give credit to any link it wants to give credit to, if it feels there are enough signals to indicate it’s a credible link. And that means even if the link is nofollowed.In my entire career I have never made a decision about whether or not I would pursue a link based upon whether or not that link would be followed or nofollowed.
I pursue links if I feel they will help my client reach a certain goal or objective.
While ‘dofollow’ links are preferred, a high quality nofollow link may contribute to rankings and will certainly be a good link to acquire. Additionally, a mixture of ‘nofollow’ and ‘dofollow’ links will result in a more natural backlink profile.
There is no ‘dofollow’ attribute, but this is the term most SEOs use to refer to links without the nofollow attribute applied.
1.3 Link Placement
It may be the case that the search engines attribute more weight to certain types of links.
For example, a text link from within content may pass more authority than a link from a sidebar or footer. This is because an in-content link is more likely to be:
- Actually clicked
- Surrounded by relevant text (see link relevancy)
Google’s ‘Reasonable Surfer’ patent, filed in 2004 and approved in 2010, suggests that Google will attempt to determine how likely a link is to be ‘clicked’ and consider this when deciding how much weight a link will pass.
That being said, there is anecdotal evidence that Google continue to give weight to links from footers, sidebars etc when the linking site is considered an authority. This recent study by Viperchill demonstrated how major brands are using footer links to influence (and dominate) search results.
1.4 The Anchor Text
The search engines have long used anchor text — that is the words used to link — as a ranking factor.
For example a web page with a target keyword of “fishing rods” is likely to benefit from a percentage of its inbound links containing that phrase; in either partial or exact match form:
- Exact match: fishing rods
- Partial match: this page about fishing rods
Ahrefs recently conducted a study across 16,000 keywords which confirmed there remains a strong correlation between keyword anchors and rankings:
We can see from the chart above that the pages at position 1 had an average of:
- 13% exact match links
- 24% partial match links
While it is clear from the data that keyword use in anchor text has a positive impact on rankings, it should also be pointed out that overuse of keyword rich anchors can have the opposite effect.
Too many anchor text links can be a sign of manipulation and may incur link penalties, such as Google Penguin.
Here is what Eric Ward had to say about anchor text:
I’m not saying that anchor text as a signal is no longer useful. What I believe is Google can make a distinction between what it considers to be a normal distribution of anchor text vs. manipulated distribution of anchor text. This doesn’t mean I try to stay within some sort of anchor text percentage or range. I have said many times that over the two decades I have been building links I’ve never once asked for specific anchor text. Not once.
Recommended reading: Everything You Ever Wanted To Know About Anchor Text.
1.5 Link Relevancy
There are a number of factors that may influence the ‘relevancy’ of a link and the weight that Google subsequently assigns to it.
- The anchor text (see above)
- Other outbound links on the page
It is also likely (and logical) that the text immediately surrounding a link is an important ranking signal.
Indeed, Google holds a patent (filed in 2004) called “Ranking based on reference contexts”, which could be construed as a blueprint for inferring context from surrounding text.
Ahrefs indexes both the surrounding text and anchor text for all backlinks discovered by our crawler.
1.6 Unnatural Links
Links which Google flags as unnatural (either algorithmically or through manual review) are likely to be discounted and not contribute towards rankings. Multiple unnatural links may also lead to a penalty and a decrease in rankings/traffic.
There is a little blurring of the lines in what constitutes an unnatural link, with some arguing that any link that is ‘built’ (even through outreach) is intended to manipulate search results and is therefore unnatural.
This is however an overly-literal interpretation of Google’s guidelines and a line often repeated by ‘black hat’ SEOs to incorrectly justify their approach to link building.
I would say that any link in which there has been an editorial choice (the site has chosen to link to you) is white hat and Google safe. This applies whether the linking site found your content organically (by themselves), or your pointed them to it (through outreach/promotion).
Links built manually for traffic reasons (e.g. guest blogging, content repurposing, content syndication) should also be safe when used as part of a wider link strategy and not abused.