Link Building

How to Qualify Link Opportunities

Article by: Matt Polsky

Breaking down what makes a link valuable is an essential skill every SEO should understand. It allows you to prioritize link-building efforts, helps uncover tactics used by competitors and even shows you what to remove or avoid.

Effectively valuing links helps do things like:

Create more valuable link-building campaigns.
Perform link audits to determine risk in a link profile.
Perform competitor analysis to understand what links drive competitor rankings.
Provide additional value and insight to teams that can impact link acquisition (digital PR and partnerships).
Determine if you should purchase a website.

Before jumping straight into evaluation, it's important to understand the history behind links and the algorithms directly impacting links.

The History of Link-Based Algorithms

Before link-based algorithms, search engines used keyword-based algorithms to determine ranking positions. Marketers could easily manipulate keyword-based algorithms by stuffing keywords in pages or even hiding them with whitewashing or cloaking.

Whitewashing is the tactic of hiding keywords on a page by blending them in with the page's background. A site owner could easily hide hundreds or thousands of keywords in the page's background (think of white text on a white background) to prevent users from seeing lists of keywords while still influencing search rankings.

Since Google provides specific user agents, a site owner could easily show Google's user agent different content for the same URL than what a user actually sees.

Both tactics of hiding or changing content for search engines are against Google's search guidelines and can get a website removed from search results.

At the time, these tactics only helped websites, which caused issues when determining quality. Google's founders Larry Page and Sergey Brin realized the problems in current search algorithms and saw a massive opportunity to create better search results by utilizing links. They named their link-based algorithm PageRank for the inventor Larry Page, and because the algorithm assigns ranks to web pages.

How to Evaluate Links

Now that you have a basic idea of why links are important, we can take a quick look at how to evaluate if a link is "good" or "bad."

Link evaluation is part data science and part common sense. Below are the primary considerations when evaluating a link's value. In later articles, we'll dive into conducting a full link audit and how to do this at scale.

Is the Link on an Authoritative Website?

Determining authority is one of the most challenging parts of the job. Years ago, Google provided some idea of this with their PageRank toolbar. However, providing the PageRank toolbar incentivized link building, which didn't align with how Google wanted the algorithm to work.

Today, a handful of tools attempt to reverse engineer the link graph and provide SEOs with an idea of how authoritative a site may be. The process is similar to Google's: each tool has a spider that crawls the web, logging links from websites they crawl into their database. They then estimate authority on a 0-100 scale.

These metrics help make informed decisions. However, keep in mind link scoring metrics are NOT from Google but from different companies that try to reverse engineer Google's link algorithm. Just because Moz says a site is a DA 91, doesn't necessarily mean Google feels the same way about that site's authority.

Here are some of the most common link indexes and their respective metrics:

Ahrefs URL Rating and Domain Rating

Ahrefs URL Rating (UR) is similar to PageRank. UR is a logarithmic formula ranging from 0 to 100, with internal and external links playing into their algorithm. The purpose of UR is to gauge an individual page's authority.

UR is a page-level metric, whereas Domain Rating (DR) is a site-wide metric. DR's purpose is to understand the potential authority of a given domain.

Ahrefs calls its link index "simplistic in comparison" to Google but is currently one of the best tools for auditing a site's links.

Majestic Trust Flow and Citation Flow

Majestic's Trust Flow (TF) is a 0-100 score to determine the quality of links pointing to a site. Majestic takes more of a "neighborhoods" approach, and sites closely linked to one of Majestic's trusted seed sites receive higher scores. Conversely, sites that may have some questionable links would see a much lower score.

Citation Flow (CF) is essentially the number of equity-passing links pointing to a site. It's not always the case, but sites with disproportionate TF to CF ratios often contain spam.

Moz Page Authority and Domain Authority

The OG of third-party link metrics comes from Moz. However, Moz is rarely my go-to tool for link analysis. Their index is much smaller than those of Ahrefs and Majestic.

Moz's Page Authority (PA) is a 0 to 100 score that predicts how well a page should perform in search based on its links. Conversely, Domain Authority (DA) is another 0 to 100 score but predicts a domain's ranking potential relative to other domains in their index.

Using a Link Analysis Tool

Depending on the goal of your link analysis, one of the most important things to remember when utilizing a link analysis tool is that you need to compare the data to direct competitors and other sites in your niche. What's normal for your niche may be entirely different for another.

Link metrics vary by niche, and you may find yourself in a niche where a tool says you're doing poorly when you're the best site in the set.

Is the Link Relevant to my Niche, Site or Page?

Relevancy is one of the most important factors when evaluating links. Relevancy isn't always black and white and can vary depending on the type of site, niche and other factors.

It may help to think of relevancy from a domain and page level. Below are a handful of examples to help explain relevancy in practice. Keep in mind that bad links can exist even with perfect relevancy, as you'll see below.

Page Relevant / Domain Not Relevant

In this case, the linking page is relevant to our page/site, but the domain is not. Examples of this include:

High-value example: Your site is about Roth IRAs and gets a link from the New York Times on a report about Roth usage. The NYT is a highly authoritative news site, and the page is specifically on Roth IRAs.
Low-value example: Your site about Roth IRAs gets a link from a page entirely about Roth IRAs on Soccer.com. Soccer.com may be authoritative but is authoritative on Soccer cleats, not financial products. If links like this come at scale, it could put both Soccer.com and your site at risk.
Moderate-value example: Your site about Roth IRAs gets a link from Chiefs.com from a page on player retirement plans. A link like this may not help a ton, but likely won't hurt.

Page Relevant / Domain Relevant

In this case, the linking page and domain are relevant to our page/site. Examples of this include:

High-value example 1: Your site about Roth IRAs gets a link from Investopedia on a report about Roth usage.
High-value example 2: Your site about Roth IRAs gets a link from Charles Schwab on a report about Roth usage.
Low-to-moderate example: Your site about Roth IRAs gets a link from investing.wordpress.com on a report about Roth usage. Typically .wordpress (or .squarespace or .wix) are free sites that get abandoned after a while, so the link is less valuable. However, ones that are consistent for years may have some value.
Low-value example: Your site about Roth IRAs gets a link from a site that duplicates content from other major personal finance sites. Links from scraper sites typically don't hurt (unless received in mass) but have no value.

Page Not Relevant / Domain Relevant

In this case, the linking page is not relevant, but the domain is. Examples of this include:

Moderate-value example: Your site about Roth IRAs gets a link from Investopedia about a charitable donation your company made. Links like this aren't bad but also don't provide immense value. I'd never turn one down but wouldn't go out of my way to build them.

Page Not Relevant / Domain Not Relevant

In this case, neither the page or domain is relevant. Examples of this include:

Low-value example: Your site about Roth IRAs gets a link from HR.com about hiring practices. There can be some value here, but it's typically very minimal. Additionally, too many of these links can negatively impact you since you're telling Google your site is about something it's not.

Does the Link have a Rel Attribute?

Within the HTML of a link, you can specify your relationship with the linked page. Google introduced this feature in 2005 to keep advertisers from receiving link spam penalties by allowing them to tag links with rel=nofollow.

Nofollow requests search crawlers not to follow the link or pass link equity or PageRank.

In 2019, Google updated its guidelines to include rel=sponsored and rel=ugc. Rel=sponsored for sponsored links and UGC for comments and user-generated content. They also now say these rel attributes, including nofollow, are only hints – likely in response to many large sites like Forbes blanket nofollowing all their links out of fear.

In the early-to-mid 2010s, Google frequently penalized sites for link building. They also penalized sites that had suspect outbound links. Major sites like Forbes, Inc and Entrepreneur (publications made successful by user contributions) mass updated their links to be nofollow out of fear that Google would penalize them for any links their contributors placed.

Ideally, any link you build from an SEO standpoint doesn't have any of these rel attributes. That said, links with a nofollow attribute are likely less problematic than a link from sponsored or UGC. With any rel attribute, just ask yourself if you'd want that link if Google didn't exist (e.g., would it send traffic).

When in Doubt, Use Common Sense

The best tool is often behind your eyes. The basic common sense checks are:

Is the placement relevant to the niche? We already covered it, but relevancy is one of the most important factors when analyzing links. Build links as if Google didn't exist – meaning the best links get clicked and add value to the user.

Is the placement relevant to the brand? Some links can be relevant to the niche but not to the brand. For example, many brands avoid sites in their niche that promote offensive opinions, no matter how authoritative.

Does the site produce quality content? Quality content from the linking site is necessary. Does that site duplicate content across the web? Are works thin with no meat or unique thought? Do works lack editorial integrity? Do they feature more guest posts than they author themselves?

Is there an active community? Community interaction is a great check when on the fence. Sites with an active community via comments or social media may fall in the more authoritative category or at least show they have real readers.

Is the site indexable? It seems like a no-brainer, right? You don't want links from a penalized site or one that doesn't allow Google to crawl it. Do a quick site search (site:exampledomain.com) and see what results come back.

At this point, you should have a solid grasp of how to evaluate links from an SEO perspective. In future articles, we'll cover the entire process of creating a link audit and how to use these insights to make recommendations and formulate a strategy.