Link building tutorial: Understanding inbound link analysis

Apart from the on-page SEO factors that include the "by the (Google) book" internal linking process of a website, external links are extremely important for organic search acquisition and are often described as "the streets between webpages" for search engines. Knowing what it takes to create a natural inbound link profile for your website is vital to avoid wasting time and more importantly, risking to be penalized by the search engines.

When Sergey Brin and Lawrence Page published their thesis "The anatomy of a large scale hypertextual web search engine" at Stanford university, they concluded that link popularity of webpages was the basic criterion for evaluating and ranking them when a search query occurred. That was the cornerstone of PageRank search algorithm.

Since then, many have changed in the algorithmic function of search engines and PageRank has gradually been devalued. Currently there are more than 200 factors that Google's search algorithm takes into account in its quest to identify the value of webpages and respond with the most relevant and authoritative results for each search query. 


How does Google evaluate inbound links?


Search engines constantly comb the web in order to identify and measure the attributes of links between webpages. While Google's private database and secret rating of link attributes remains an estimation, according to moz team "analysis of patent applications, years of experience and hands-on testing have contributed to some intelligent assumptions that apply in the real world". Below i will attempt to summarize the most notable factors SEOs have concluded that Google measures when assessing the link equity of a website:
  • Global link popularity. It is considered as the firepower of webpage ranking and represents the total link equity of a website, as this results from the quality and quantity of incoming links.
  • Freshness, sustainability and growth in the number of links, also know as Velocity or Trajectory. Many tools such as majestic offer detailed information and graphical representation of such metrics.
  • Diversity of linking domains. The number of domains linking to a webpage that ideally should be no less than 10% of total number of links)
  • Domain of the linking site. Usually most linking sites have a TLD of .com, but links from sites with TLDs such as .gov, .edu and .org are considered more trusted from search engines and high value. Backlinks from Country-specific TLDs influence local rankings.
  • Page & Domain Authority of the linking site. ( You can find a still valid explanatory session from 2009)
  • Trust of the linking site. Is it from trusted or "bad" neighborhoods?
  • Relevancy of the linking site. Topical relevency of external links to your site is becoming increasingly important. Therefore, forget links from irrelevant content. For example links from site with cooking content to sites with technology or law related content.
  • Anchor text of the link. The purpose here is to diversify anchor texts so that exact or broad keyword match in anchor text should ideally be 15-30%, although this percentage will become minimal in the future.
  • Purpose of the link. Basic categories of backlinks include editorial links, navigation links and paid textlinks, with the first two categories to be favored by Google.
  • Age of the link. Old and new links both serve different purposes and are considered valuable. 
  • Links from social sharing. It remains controversial whether there is any effect on organic rankings for backlinks from social networks, though the social networks offering "do-follow" links are more likely to correlate with higher rankings.
In short, all factors are important to evaluate when conducting link building or analysis, but the quantity and quality of inbound links are perhaps the most notable. And while the incoming link quantity may have no negative effect on rankings, link quality is a factor that Google has been focusing on over the last years and you should be very cautious what links you seek for. 


Link Building & Negative SEO: The fastest way to Google penalty


The principles of negative SEO are closely related to the intentional triggering of Google penalties. In online markets with harsh competition, some players often implement strategies such as spammy link injection, through which they target their competitors websites by attempting to trigger a Google penalty. There are several types of links that "annoy" Google such as:

  • Links from pages with excessive outbound links also known as link farms. Most of these sites are inactive (parked) domains. 
  • Links from websites with the same IP/C-class. Usually links created by the same person.
  • Over-optimized anchor text and lack of anchor diversity.
  • Links from irrelevant websites in terms of content relevance. Although this tactic is not an actual reason for penalty, according to the network theory it dissolves the thematical entity of a website.
  • Links from bad neighborhoods. Bad neighborhoods are mainly considered the 3Ps types of "toxic"' websites (pills-poker-porn) and spammy link directories. 
  • Private link networks and sites that have acquired links from them are subject to manual penalties from Google web spam, once uncovered. AngloRank has been a recent such case. You can read more on link networks.
In addition, Google's guidelines for "link schemes" outline in detail which link building tactics violate their policies. In brief, presented below: 


  • Large-scale article marketing. (publishing the exact same content such as a press release in many sites) 
  • Reciprocal linking. Exchanging links with other webmasters in a "link to me and i ll link back to you" manner. 
  • Use of link building automation software which is currently the core business of black hat SEO.
  • Buying and selling links. Though this depents on the type of link, since links created through native advertising are almost impossible to be identified by the search engines.
  • Anchor text over-optimization. Using the same anchor text with the exact match of the keyword you want to rank for.
  • Bookmarking and directory submission. These kind of links have been abused by webmasters and are currently considered low value.
  • Widely distributed links in site footers, webdesign templates, embedded widgets and infographics.
  • Low quality comments in forums and blogs. These are the easiest to acquire and therefore Google graded them as low or no value.
  • Guest blogging (recently declared as "done" by Google's evangelist Matt Cutts, but still in debate among many industry experts)

So, by now you should be wondering if there is any correct tactic left... Well, the answer is: Not Many! The infographic shown below illustrates a summary of which tactics should be avoided and defines what is the current correct implementation should you want to maintain a natural backlink profile. As you probably have guessed, all of these tactics that today are considered natural, are subject to change due to the increasing number of updates in Google search algorithm.  


Link building and backlink profiles
Source: Greenpal


Revoke your link building actions using The Disavow Tool: Scalpel or Machette?


For websites that violate Google's guidelines and have repented for their tactics, Google offers a controversial tool called the Disavow Tool in webmaster tools, which is used for cutting off the "toxic" inbound links to a website. Disavowing links is considered a radical action and the tool should be used with caution as recall is impossible especially in cases of disavowing all links from a certain domain. 

A key point here is that Google expects from the webmasters who decide to use the tool, to show determination and use it like a machete rather than a scalpel trying to disavow only individual URLs from a domain that include toxic links. Once finished, webmasters should claim from Google's webspam team to reconsider the site that it might take up to 6 weeks with a turnaround time of around one week.


Modern link building is in transition and webmasters should adapt to changes that are imposed by the search algorithm updates. Maintaining a low-risk and proactive manner in link building can help websites grow stress free (until further notice).

April 14, by Vangelis Kovaios


Suggested Reading:    

What has changed in 2013 for link building tactics