Link Building for SEO: Everything You Should Know

Contents

What Is Link Building and Why It Matters

Ever wondered how Google became the most popular search engine in the world? A large part of its early success and explosive growth was due to its innovative approach to ranking search results: instead of relying solely on a web page’s content to determine its relevance, the young search engine deployed a new ranking factor: authority.

Authority is meant to gauge how “respected” a web page is among all existing web pages, using the mechanism of referencing by hyperlinks, i.e. what we now call simply links. The underlying assumption goes like this: if a certain page uses some of its precious space to present a link to another page, it must believe that there is some value in that referenced information.

By casting such a vote, the linking page thus passes some authority (or “link juice”, as SEO jargon puts it) to the linked page. The more aggregate authority is passed to a certain page via incoming links, the more important it must be as a piece of information. Search engines, which strive to present the most useful content to their visitors, use the authority flows described above to determine the relative prominence of each web page.

Within this context, it’s not hard to understand why website owners and online marketers are so intent on getting new incoming links: it was the original guiding principle of the search engines’ ranking algorithms, and it is very much valid today.

However, it is worth noting that the exact way Google accounts for the authority flows has changed a lot as the system grew more and more sophisticated, in order to prevent artificial manipulation of rankings by unscrupulous folks. Understanding the concept of link quality will not only help build a better link profile, but also avoid any sanctions by the search engines.

The Difference Between High- And Low-Quality Links

In order to understand why links can be of varying quality, let’s start with looking at what Google itself has to say on this matter:

Any links intended to manipulate […] a site’s ranking in Google search results may be considered part of a link scheme and a violation of Google’s Webmaster Guidelines. This includes any behavior that manipulates links to your site or outgoing links from your site.

This might sound weird, since it looks like virtually every intention to get an incoming link might be considered as a violation of these guidelines. If we read the statement more carefully, though, we’ll notice one interesting nuance: the word may. This little circumstance adds new rules to the game by creating a broad spectrum for the activity. This “wiggle room” will determine whether your backlink building campaign will bring you high- or low-quality links.

In the same document as cited above, Google goes on to state that the best way to gain high quality links is by creating “unique and relevant content”. In other words, the more useful your content is to your visitors, the more chances that someone will link to it, sometimes even without your explicit request.

Given the above, here’s how we can draw the line between good and bad backlinks:

– High-quality links are editorially controlled by the linking site
– Low-quality links have been placed without editorial control

Following the editorial principle will help ensure that the links you get are future-proof and will not land you a search engine penalty someday. This, however, begs the question: are all non-editorial links automatically low-quality?

Surely not. If you share your content on social media platforms, for example, you still get links to your website, but these are focused on promotion, not manipulating search positions. Furthermore, as your website and the things it is offering become more popular on the web, it will inevitably get some natural links, some of which will originate from non-moderated platforms. This is okay as long as you’re not doing that yourself on a massive scale.

Modern Link Building Strategies

Now that we’ve established the basic principles behind link authority and quality, let’s look at some of the most commonly used link-building mechanisms that have been time-tested and still work to this day.

Linkable assets: instead of pushing others to link to your content, it is often much more efficient in the long run to create content that people will want to link to in the first place. There are many types of content with potential of becoming linkable assets, the primary idea here is to create the needed intent, i.e. ask yourself the questions: “what would people link to when they create their own content?” and “why would anyone link to this piece of content?”. Some of the most powerful linking intents include:

• Permanently relevant information such as how-to’s and in-depth guides (no wonder WikiHow has thousands of backlinks).
• Authoritative summaries that feature contributions by top influencers or data from respected sources in an easily digestible manner.
• Useful tools and applications that help users perform tasks like searching, generating, analyzing etc. An example of such online tool is our free WordPress Theme Detector.

It is worth noting that linkable assets don’t need to be created entirely by you – some of the effort can be crowdsourced if you can come up with a way to make contributing fun or useful for third parties. For example, the startup incubator Ycombinator created this Hacker News list where users can submit new articles as well as upvote and downvote existing news, adding content and increasing the social relevance of the page at the same time. Another example is the job board created by ProBlogger: far from being their core business, it still attracts tons of backlinks because it provides real value to the industry.

Creating superior content: this one is closely related to the previous technique, because the basic premise is similar – coming up with top-quality content, only in this case it entails determining the most prominent pieces of content on a specific topic (keyword group) and creating an even more comprehensive one.

This method is often called the “skyscraper technique” in SEO lingo since it feels somewhat similar to building additional levels to construct the tallest building in the city; the metaphor goes even further when we consider that only the highest edifice tends to get all the attention in a given area, “second tallest” and “third tallest” are much less enticing names. Having the absolutely best content will help you land links more easily, especially if you couple it with unique linkable assets (wizards, search tools, and other interactive helpers) or media (videos, infographics, podcasts etc).

Not only can you borrow structural ideas from your established competitors on the stage of composing your new “skyscraper” page – you can also use their link profiles to scout for easy link prospects: after all, a site that has already linked to a competitor’s post will be more likely to link to your (superior) piece as well!

Guest posting, or writing a piece of content for a third-party blog. Backlinks can be had either from the body of the text or from the “author bio” section underneath it. This is probably one of the oldest and most popular link building techniques on this list, yet lately there’s been a fair degree of debating and overall controversy around it.

To avoid getting drowned in a similar discussion, it is worth specifying that the key ingredient of a solid guest posting campaign is the quality and authority of blogs chosen as potential hosts: the mere fact that a blog is accepting contributions from outsiders does not mean you should rush to publish a piece of content on it. Instead, in the long run it pays to be picky and pitch only to websites with a permanent audience (i.e. stable traffic), high-quality existing content that is regularly updated, and a strong brand (ideally).

Finding guest post prospects can be as simple as searching for specific keywords like write for us [your niche] or using specialized aggregators such as Guest Post Tracker. In addition to that, it is worth manually checking each established website in your niche (of which you should be aware anyway) for the presence of a blog – many will have a “write for us” notice on their website, but there’s also a fair chance that your high-quality content will be accepted even if a blog doesn’t have explicit calls for third-party contributors.

Infographics and other media: this one’s similar to linkable assets mentioned above, but instead of building useful pages on your domain that others might naturally want to link to, you can create graphics and video that other websites will want to embed into their posts. While the fact of an infographic being used in a third-party article does not guarantee you a backlink, two features of this method work in your favor: firstly, since making another copy of an image costs nothing, the sheer scope of the potential distribution of your media means there are significant chances of at least some part of publishers mentioning the source.

Secondly, you have the possibility to recover some of the link-less media by e.g. doing an image search in Google using your infographic. You can then reach out to each blog which has not linked back with a friendly request to do that, and chances are many decent ones will gladly do so (if a webmaster refuses to add an attribution to your work, you might not want a link from their blog in the first place since they might also be using other duplicate content across the board).

Monitoring brand mentions: apart from looking in search engines for users of your media content, why not also keep tap of any instances where your brand is being mentioned across the web – after all, if your brand name is unique enough anyone referring to it must be explicitly referring to your website. This means you can contact them and request a linked mention, which, statistically, will see some positive results, giving you extra backlinks from places that are almost by definition contextually related to your brand.

The easiest way to track brand mentions is by using specialized tools; our favorite is the Alerts tool by Ahrefs, which allows compiling a list of keywords for an automated system to monitor across the web. Once a new piece of content is found which contains your target words or phrases, you will be sent an email alert with the details.

Broken link recovery: we’ve talked about recovering links that are implicitly or explicitly connected with your website, yet there’s another useful technique worth mentioning that takes it a step further. Large and complex websites will almost inevitably have a certain proportion of outbound links that do not work anymore – it might be that the specific page they are linking to has moved or no longer exists, or maybe the entire website is no longer live. In any case, such links hurt user experience, which means webmasters will be happy to correct them.

As you might imagine, there are two important components to this link building method: finding the broken links on other websites and making sure you have your own pages to replace them. The first part can be approached from two angles – either finding pages with lots of links such as “Useful Resources” lists (they will typically be the ones with higher probability of containing broken links) or taking a specific large site and scanning all of its pages for non-functioning outbound links.

For the first approach, you can use search queries like useful links, useful resources, etc, ideally within your niche, and then scanning the pages you find with tools like the Check My Links Chrome extension. The second approach is most easily implemented with Ahrefs (yes, we do fancy this toolkit) by running a website through its Site Explorer tool and checking the “Broken links” sections in the “Backlinks” and “Outbound links” reports (you can see more information and screenshots in this official guide).

Once you have a list of broken links, you can filter out those that fit with your existing content, and then consider creating new content to fit the remaining ones, where feasible. After that, you’re ready to reach out to the webmasters and help them fix their broken links by substituting them with your resources. The most important thing to keep in mind here is that your substitute content should absolutely be of high quality and as close to the original links as possible.

Risky Link Building Tactics You Better Avoid

To avoid both manual and automatic downgrades of your website by the search engines, here are some link-building strategies you should abstain from:

Comment spam implies leaving comments on blog posts which either allow inserting links into the comment body or linking the comment author’s name. If you’re running a blog, you’ve most likely gotten a lot of comments along these lines:

Doing a quick Google search for the same phrase gives you thousands of results with identical wording (i.e. non-unique content):

To see why comment spam on a large scale is a useless (and potentially dangerous) SEO tactic, let’s consider the possible scenarios based on two factors: whether a blog moderates the comments before making them public and whether the comment links are dofollow –

• Moderated, nofollow links – even if your comment does get approved eventually, any links inside it will be nofollow, i.e. not tracked by the search engine bots. This kind of defeats the entire purpose of the enterprise.
• Moderated, dofollow links – such blogs are quite rare nowadays, and if you do find some from your niche, you’ll need your comment (and the contained link) to really be unique and have value-added to get approved. This is very difficult to implement on a massive scale, and is still less preferable than full-fledged content submissions such as guest posts.
• Unmoderated, dofollow links – a magnet to various spammers, so over time such pages become so littered with comments linking to all kinds of non-topical websites, that being in such a crowded, low-authority company is not what you want for your links.
• Unmoderated, nofollow links – the “worst of both worlds”, no explanation required.

In total, this implies that mass-spamming other blogs with backlink-containing comments is both impractical and risky.

Forum spam is another similar tactic, which can take the form of putting the link within your signature or post’s body or creating a bunch of fake profiles that post links to your web resource. Either way, it’s a useless strategy to say the least, even if the forum is a respected and moderated one: since forum threads tend to include multiple replies, and since you’re not the only one doing this, your outgoing links will be on the same page with dozens of other (mostly irrelevant, and sometimes low-quality) outgoing links – not very useful when it comes to passing authority.

Low-quality directories are apparently still a thing, considering the number of offers on freelance marketplaces to “place your link in 300 directories for $10”. While this might look like a real bargain, beware that it might also get you penalized by the search engines: directories that accept mass submissions, especially unmoderated ones, are places where mostly low-quality websites will hoard, thus creating very shady surroundings from your links.

In general, though, even moderated directories with paid entry are not the smartest way to build effective links nowadays, as Google gives more and more preference to user value and engagement. They had a blast in the early years of the Web, but now it’s about time we said goodbye to this SEO tactic.

Private Blog Networks, or PBNs, are another place where you don’t want your backlinks to live. A PBN is an interlinked group of websites (usually built on recycled expired domains) owned by the same entity carefully disguised as independent blogs in order to pass link authority in a pre-defined manner. Google has been penalizing PBNs heavily since 2014, and while their tactics did become more refined over time, the search giant still allegedly has little trouble identifying such structures, given the gargantuan amounts of data and processing power it wields.

As a webmaster, though, you might be wondering how to actually tell if the website you’re looking to publish on is a part of a private blog network in the first place. As mentioned earlier, the PBNs that do survive to the present day are more sophisticated than their ancestors, but there are some telltale signs you’re dealing with one:

• Thin and superficial content: since PBN constituents are usually created by buying expired domains and fulling them with new content, such content is usually produced at scale, and at the lowest possible cost. You can quickly tell from the quantity and quality of the available content if a website is intended for real people or is just there to pass link juice.
• Domain name that does not quite fit the content: while PBN owners try to search for expired domains that match their target niche, it’s not always possible to obtain such in needed quantities – which means some of the blogs in the network will have strange-looking domain names that have little relevance to their main topic.
• Another website used to be on the same domain: if you have suspicions, you can use the Wayback Machine to check if the same domain used to have a completely unrelated website on it earlier.
• Very little multimedia: unique media is more difficult to produce at scale than text, so PBN blogs will have much less (or none) of it compared to legit websites.
• Abnormal backlink profile: if you check the backlinks of a PBN constituent by a specialized tool such as Ahrefs Site Explorer, you’ll notice certain patterns such as large numbers of broken links, stale or negative link growth over the past year, as well as incoming links that are not relevant to the current topic of the blog. These are all red flags which indicate a PBN candidate.
• You’re being offered backlinks from a dozen blogs by the same person: maintaining a high-quality blog is a laborious task, and while many web entrepreneurs do handle multiple websites, it’s very rare that a single organization disperses itself into more than a couple of these. Anyone offering you simultaneous placement on 20 blogs is most probably a PBN owner.

Link Penalties and How to Recover from Them

Most SEO experts think that low-quality links are not taken too seriously by Google and other search engines. After all, you can never have 100% control over the process of external pages linking to your web resource. However, despite the fact that in most cases unintended or occasional bad links do tend to get devalued rather than sink your rankings, when used on a massive scale those can still be quite harmful.

Back in 2012 Google released the first Penguin algorithm update – a weapon of mass destruction for low-quality links, with the abusing sites becoming confined to the fringes of the web. Since that time, several more iterations of Penguin have been released, each next being smarter at identifying shady link-building strategies. The latest version, 4.0, is claimed by Google to be a real-time and page-specific feature – in other words, the search engine now wields laser precision when it comes to identifying and punishing low-quality links.

There are two types of penalties that Google can bring down on a web page that has been caught on link spam – algorithmic and manual:

Algorithmic penalty, as you’ve probably guessed from the name, involves no humans in reviewing potentially bad links. Most of those are passed by the Penguin algorithms we’ve discussed above. Is there a way to determine whether your website has been hit by an algorithmic link action? Unfortunately, you won’t get any notifications – it works “in the background”, and all you’ll see will be precipitous SERP declines over a short period of time.

Manual penalty, in contrast the previous one, is applied by someone from Google’s Webspam Team. It could be triggered by: a spam report from someone else, you being in a competitive niche actively monitored by Google, or some suspicious aspect in your link profile.

How do you determine that you’ve been hit by a manual link penalty? Easily – you will get an email notification from Google. In general, though, it doesn’t matter what type of penalty you’ve been stricken by – both types lead to a drop in SERPs and consequently a drop in traffic. The worse-case scenario is being de-indexed, i.e. disappearing from the search results entirely.

In general, though, it doesn’t matter what type of penalty you’ve been stricken by – both types lead to a drop in SERPs and consequently a drop in traffic. The worse-case scenario is being de-indexed, i.e. disappearing from the search results entirely.

What should you do if you’ve actually been hit by a link penalty (i.e. experienced a sharp drop in rankings and/or got a manual action notice from Google)? First thing to do is clean up the mess by removing the low-quality links or telling Google which links should not be taken into account, in case you’re unable to remove them for one or another reason. Below we’ll provide a detailed sequence of steps involving Ahrefs’ SEO toolkit; we will assume that you have already added your website to the Ahrefs Dashboard (by using the “+ Add a website” button):

1. Generate a list of links to your website using the Site Explorer tool by inputting your website’s URL (or simply clicking on your website’s name in the Dashboard). From the overview, click on “Backlinks” in the left menu to see the incoming links.
2. Find low-quality links by analyzing each inbound link from the list, based on what we’ve discussed above about link quality; pay special attention to the following: links from websites outside of your niche, links from shabby-looking pages, links with weird domain names, links with anchors that seem to be spammy, links from websites you can’t recognize.
3. Create a disavow file containing a list of links that you consider detrimental to your website. You can do it manually or use the built-in functionality right inside the Site Explorer’s “Backlinks” view: when you find a link you’d like to add to the Disavow, tick the checkbox next to it and click on “Disavow domains” button that appears above the table of links. After you’ve gone through all your backlinks, return to the Dashboard and hit “Disavow links” in the row that lists your website. In the next screen, click on “Export” in the top right corner, then tick the “Save as TXT for upload to Google Disavow Tool” option and hit “Ok”.
4. Upload the disavow file to Google through the interface available in the Google Disavow tool. Each time you upload a new version of the disavow file, it’s better to be on the safe side and repeat all previously disavowed links in the new uploads as well.

If you’re under a manual penalty, you should’ve also received an email stating the reason, and the same email will contain a link to the section of Google Webmaster Tools (if you’re still not using this instrument, go create an account right now!) which allows you to send a reconsideration request after you’ve cleaned up the faulty links. In case you’re facing an algo penalty, the only thing left to do is wait until Google notices the positive changes in your link profile and corrects its earlier decisions regarding your rankings. This can take anywhere from several weeks to several months, during which time you are advised to closely monitor your SERPs and incoming organic traffic for signs of improvement.

Keeping Your Link Profile Natural

As you’ve seen above, dealing with link penalties is never a pleasant work. This means it’s worth making every effort to avoid getting penalized in the first place. How do search engines decide which websites to punish for their backlinks and when? The exact details of their algorithms are never disclosed, yet the overall principle is easy to come by: they aim at distinguishing between sites that get their links naturally (i.e. thanks to being useful to others), and those that employ manipulative tactics with the sole aim of ranking higher.

A natural-looking link profile is therefore something any webmaster should be striving towards when they decide to engage in active link-building campaigns. “Naturality” should be present at both the individual link level and the overall link profile of the website. First, let’s go over the properties of each standalone inbound link:

• Position on the page – the most natural way to include links to other resources is inside the main content of a page or post; links from sidebars, header (especially navigation menus) as well as footers look much more suspicious and should therefore be handled with extreme caution.
• Surroundings – a link that just sits there on a page by its own might look less natural than the one embedded into a text. That text should also, of course, be relevant to the links (yes, search engines can easily gauge relevance nowadays, using their vast training datasets).
• Anchor – the text of the link itself should, too, be relevant to its surroundings and of course to the external page it leads to. Brand mentions or generic anchors (such as “here” or “more information”) are usually safer than clearly keyword-optimized link text (i.e. using an entire keyphrase as an anchor).
• Visibility – if a webmaster adds an outbound link consciously and really endorses the target page, they will never think of hiding or obstructing the link in any way. For that reason, backlinks hidden with styling methods like extremely small font size or text color that is almost indistinguishable from the page background, are clear red flags.
• Forwarded traffic – if the page that contains the backlink receives any visitors at all, some of them are likely to follow the link if it’s relevant, useful, and otherwise satisfies the above criteria; therefore, if a backlink sends some real visitors your way, it is not only good for your inbound traffic, but also a sign to the search engine bots that the backlink is legit.

Apart from that, it is worthwhile considering the entirety of your incoming links as a single statistical group and making sure that the following criteria are not skewed and don’t look suspicious:

• Anchor composition – diversity, frequency of occurrence, as well as specific keywords are important here: instead of containing only keyword-optimized anchors, branded links, generic anchors and URL anchors (that’s when a full web address is used as a link text) should typically be expected to prevail in a natural link profile.
• Dofollow/nofollow proportions – while most SEO campaigns are focused on obtaining links without the “nofollow” attribute, i.e. those that are counted by the search engines towards your website’s overall inbound authority, it is unwise to think to Google and others don’t “see” them at all – websites with only dofollow links pointing at them can easily be considered as candidates for link manipulation and therefore receive further close “inspection” (you don’t want that to happen to your site, for sure).
• Inbound authority distribution – statistical principles such as the Law of Large Numbers and the Central limit theorem imply that a website with many backlinks will almost inevitably have more weaker backlinks that stronger ones (after all, there are much more sites with low authority on the web). A situation when most of your inbound links come from pages with extremely high authority parameters doesn’t look natural, rather smells of over-optimization.
• Evolution with time – apart from the link profile being balanced at any given point in time, it is also worth noting that sudden changes in any of the above parameters will raise doubts as to the absence of active manipulation from your side. In other words, strong and future-proof link profiles are built gradually and steadily over significant periods – months and years, certainly not days or weeks.

All of the above are easily monitored with the Site Explorer tool by Ahrefs we’ve mentioned earlier: most of the times, you can spot a website with a suspicious backlink profile by simply looking at the dashboard result of this tool’s analysis. Additional insights can be obtained by going through the specific sections of the Site Explorer report.

Don’t Forget about Outgoing Links

While most of SEO focuses on incoming links (which is totally understandable, given their influence on the search results rankings), we couldn’t skip outbound links in this guide because they also play a vital role in determining the level of authority of a page and even the entire website.

In order to play it safe it terms of linking out, it’s recommended to keep the following simple principles in mind:

• Avoid out-of-context outbound links, especially to websites outside of your niche – Google has become quite good at gauging the meaning of a given text, so it’s also easy for the search engine to determine if a linked resource has anything to do with the topic being discussed in the text.
• Don’t link to low-quality content – no matter if it’s been done intentionally or by mistake, linking to shady, hacked, or malware-infested websites is a big red flag for Google; since the websites you link to are also part of your “link surroundings” on par with inbound links, being “surrounded” with low-quality websites is not what you want when optimizing your pages for best search result performance.
• Avoid hiding outbound links, search engine crawlers will find them in any case because they look at the code, not the visual representation of a page.
• Fight comment spam on your own pages – just like you don’t want your backlink to be in a “bad company” of dozens of other shady links on someone’s page, it’s not a good idea to allow for such a “link fest” on your own blog posts as well.
• Fix broken outbound links – such sloppiness simply tells Google that the website is not being well-maintained.

Build a Future-Proof Link Profile

As you’ve seen above, correcting your link-building mistakes can be a tedious, slow, and painful process – that’s why it is always advisable to play it safe right from the start and keep an eye on the quality of your incoming and outgoing links at all times. A more modest, but healthier link profile containing only high-quality links is much more preferable and safer in the long run than a bloated backlink base built with questionable methods. Keep that in mind and search traffic will follow!

Left with unanswered questions? Have something to add? Feel free to share your thoughts in a comment section below and of course don’t hesitate to tell your friends about this guide on your social media channels :)