The role of links in search engine optimization (SEO) has created an entire ecosystem of discussions on the web ranging from research to rumors. If you skim through various articles on SEO, you’ll undoubtedly see lots of mentions of “high- and low-quality links”. This makes one wonder: why is there such a distinction, and why “low-quality” links are bad in terms of your website’s rankings?

These two questions seem to be a bit vague in their initial form, and we can’t give answers to them out of thin air – let’s investigate this subject in more detail instead. Because of all the existing (and often contradictory) information connected with this complicated topic, we’ll start with the basics and gradually cover all important aspects that are related to link quality.

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

Sounds simple, right? But what exactly is an editorially controlled link? In order to play on the safe side, here are some of the types that are currently penalty-proof if done correctly:

  • Guest blogging: the website you’re introducing your content to always has a choice to decline or modify it, and as a result, you have a chance of getting a link, but it’s not 100%. What’s important, though, is that all links you use in your content go through the editor and the publisher of the blog you’re pitching to.
  • Blog commenting: leaving comments under relevant blog posts will rarely get you links that pass authority, but they pass the “editorial” criterion: on the one hand, you have the right to post any comment you want (except ones that violate the blog’s rules), on the other hand, only useful and authentic comments get approved. This implies, of course, that the blog moderates its comments before publishing them – in almost all other cases comment feeds quickly turn into garbage-dumps of old-school spammy SEO trials. You don’t want to be in that crowd.
  • Moderated directories: just like with comments, you should choose only those directories that have editorial control over each submission request they get. By doing so, they reduce the number of low quality sites that want to appear in the listings solely for the sake of free links.
  • Online communities: again, every useless or spammy material will be deleted or downvoted by the moderators, so choose the platforms wisely and post relevant things.
  • Press releases: these are not so much focused on links, rather on PR – but if your content is genuinely newsworthy, it will be caught by the press and you might get “source”-type links back to your website.

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.

Now that we’ve established some basic principles of “link goodness” it is time to find out how low-quality links can impact your search engine rankings (SERPs).

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.

To avoid both manual and automatic penalties, here are some types of links you should generally avoid:

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.

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.

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.

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. Adhere to proper link hygiene 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 :)

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