SEOmoz │ The Professional’s Guide to LinkBuilding
©2007 SEOmoz, LLC
Sections
- Why Search Engines Measure Links
- An Introduction To LinkBuilding
- Why Build Links?
- How Do Search Engines Measure Link Quality?
- Searching the Engines for High-Quality Links
- Competitive Link Research
- The Art & Science of Direct Link Acquisition
- SocialMediaLinkBuilding
- LinkBuildingwith News, Blogs & Feeds
- ContentBuilding for Links
- Leveraging Partnership Networks
- Directory Submissions
- Article Writing & Submission
- Forum & Community Links
- Public Relations & Press Releases
- Charity & Donations
- Pay-Per-Click—Buying Traffic for Links
- Web Design & Development Portals
- Local Link Opportunities
- Political Associations
- Link Brokers
- Direct Link Buys
- Become a Product/Site Reviewer
- Automated LinkBuilding (aka Link Spamming)
- Link Tracking & Success
Preface
Link building is one of the first tasks thrust upon marketers new to the web. Among the most time-consuming and frequently frustrating of all Internet marketing obligations, link building is, nonetheless, critical to the success of businesses of all sizes. The goals of link building are centered on improving the visibility, reach & accessibility of web content. Since links are the web's primary system for directing traffic; the marketer's focus must be to improve their ability to drive that traffic – links create credibility, visibility & direction for the www's audience.
This article is intended to serve as a comprehensive guide to link building. The first three sections cover the basic structure and function of links, including why they are important and how they are used by the search engines to establish search rankings. Sections four through six discuss research strategies aimed at helping you determine the most valuable targets for link building in your particular niche or industry. The remaining sections (7-24) provide specific link building strategies you can leverage for your sites(s).
Section I
Why Search Engines Measure Links
PageRank and Links as Votes:
Larry Page and Sergey Brin publicly pioneered the use of link measurement as an indicator of search relevance when they created the Google search engine. The initial idea behind their legendary PageRank system was that a link to a particular page is equivalent to a vote by the linking page for the linked-to page.
As the theory goes, by measuring not only the keyword relevance on a page, but also the number of “votes” it had, you could accurately determine which pages were considered by the web’s users to be most valuable for the given search terms. Furthermore, links from web pages with high PageRank would be more valuable (considered more authoritative and reliable) than links from low PageRank pages.
This initial model, while revolutionary, didn’t consider the quality of on-page content, trust metrics or semantic relationships and was thus extremely vulnerable to manipulation.
SEOmoz homepage with Google Toolbar showing Page Rank 6:
Improvements in Link Quality Scoring:
Over the years all of the major search engines adopted the link-based ranking model with some stylistic variation from engine to engine. The technology, quality and “intelligence” of the various search algorithms continually evolve in an effort to improve the quality of returned search results.
Anchor text is now considered when evaluating the relevance of a given link to the given keywords. If a site about Seattle Boat Tours has lots of links pointing to it with anchor text written as ‘Seattle boat tours’, those links will provide greater value to the link recipient than links with anchor text such as ‘click here’ (at least for searches on “Seattle Boat Tours”). We will discuss anchor text in greater detail in the next section.
Semantic attributes the of on-page text surrounding links is also analyzed. For instance, if a link to Seattle Boat Tours is in the middle of a page about theoretical physics as it relates to the study of Scientology, that link won’t be considered as valuable as the same link with adjacent content about Seattle, tourism, boating, etc.
Seattle.gov tourism page, this would be highly relevant for ‘Seattle Boat Tours’
Search algorithms also consider relationships between linked sites. By analyzing things like IP addresses, reciprocal links and domain registration information, the engines try to determine if the links are valuable organic links, or if they are manipulative, artificial links created solely for ranking purposes.
Links as Quality Control:
By using the methods discussed above to measure link quantity and quality, the search engines create a ranking system that is much harder to manipulate than one based solely upon on-page factors. That is not to say, however, that page structure and actual content are not evaluated.The link-based model simply places more importance on links based upon the theory that only well-designed, content-rich pages will get high-value links from reputable sources.
Trusted Domains:
Link factors such as anchor text, semantic relevance and page relationship certainly matter, but perhaps no factor matters as much as the trustworthiness of the domain providing you with your link. A single link from CNN or The New York Times is worth more “link-juice” than dozens of similar links from no-name blogs and MySpace pages.
Trusted domains have proven over time (ironically, through the acquisition of thousands of trusted links) to be worthwhile and reliable sources of quality information about their given subject matter. As such, when the search engines see that these sites link to you when discussing your area of focus, they pay attention. This tells the engines that a reliable and trusted source thinks you are an expert and you offer content that’s extremely relevant to the topic.
Think about it this way: If the Weekly World News runs the headline ‘Two-headed Dragon Boy Born in New Jersey,’ would you take it seriously? No? What if the same headline was on the cover of Time magazine? In nearly everyone’s mind, the Time link to ‘Two-headed Dragon Boy Born in New Jersey’ is far more valuable and credible than the same story from the Weekly World News.
This is why we don’t go into a state of shock when we see bizarre WWN headlines every week in the grocery checkout line: they’re simply not reliable for anything other than a laugh. In the online world, the search engines use their artificial intelligence algorithms to make similar determinations. Thus, 50 links from Moe-does-Mortgage.com is not nearly as valuable as one link from Bankrate.com or CNN’s money.com.
This is a self-perpetuating process on the web. The more trusted, valuable links your site receives, the more trusted and valuable your site (and the links you give) becomes.
Section II
An Introduction to LinkBuilding
Fundamental Properties of a Link:
If you’re reading this (and you are) then chances are you know what a link is. As such, we’re going to skip the lecture on HTML and the structure of the Internet (it’s a series of tubes). What we will discuss are the important on-page and structural characteristics of links that can help make them most effective: anchor text, link location and link intention.
Anchor Text:
Anchor text is the actual text that visitors click on to follow a link. Below are three examples of anchor text for a link to the SEOmoz homepage:
1. For great info about search engine optimization, check out
2. For great info about search engine optimization click here.
3. Here’s a great resource for info about search engine optimization.
Of these examples, both 1 and 3 have distinct advantages over number 2. Number two provides a link (which is good) but it offers absolutely no semantic value. SEOmoz isn’t a respected resource on “click” or “here.” These aren’t keywords or search terms anyone would use to find SEOmoz, therefore there’s no keyword benefit conveyed by this anchor text.
Example 1 does contain SEOmoz’s name (since it’s in the domain name). This helps some, but chances are we wouldn’t need much help if someone were searching for ‘SEOmoz’ directly. Note though that constructing concise, relevant URLs for the pages on your site can help, not only for links of this style, but for keyword relevance in search engine spidering. If an article page has the URL it conveys no value about the content of the article, whereas provides context and relevance to anyone searching for “holiday boat cruises.”
Example 3 is certainly the best of the three because it not only provides the link but it also offers additional semantic relevance. If the search engines see that a lot of links to SEOmoz use anchor text such as ‘search engine optimization,’ they will quickly recognize that other web pages think SEOmoz is a relevant source for information related to those keywords. Whenever possible, links that carry semantic value (such as example 3) are preferable.
URL Location:
This refers to where in a site’s page structure your link is found: shallow or deep. Shallow links are links to your site’s homepage or top-level category pages. Deep links, on the other hand, are links to more specific pages such as individual articles, blog posts, tools or other content.
Deep links are usually the result of people finding your deep page content useful and wanting to share it with their visitors. Search engines like these types of links; they’re natural and often more valid. Shallow links, when too prevalent, tend to look spammy to the engines. If hundreds (or thousands) of sites are linking to you, and more than 80% link exclusively to your homepage, the search engines may cast suspicion on the “validity” of those links. Aggressive link builders would be wise not to abuse homepage-only linking. Keep in mind that this is much more important for larger sites since small sites do not have much inherent depth.
You can check your deep link percentage by visiting Yahoo! and performing a link search. Type in the search as “linkdomain: using your homepage URL.
Yahoo! Site Explorer linkdata for the entire SEOmoz site and homepage only, respectively:
In the screen captures above you’ll see that SEOmoz has 304,262 links to the entire site but only 32,034 to the homepage, “ As such, almost 90% of links to SEOmoz are to deep content pages.
Also important is the location of the link on the linking page. Are you being linked to from someone’s homepage, an advertising page or a relevant, high-quality content page? Links from a link directory or advertising pages are often paid, reciprocal or otherwise externally influenced and therefore less legitimate than deep links from within actual content or more specific, topical pages.
Conversely, the more popular, specific and well-linked-to the page is that links out to you, the more valuable that link will be.
Link Intention:
What you should always keep in mind when considering the relative search engine value of a given link is: how will the engines view this link’s value to searchers? What is the linking page’s intention?
If it’s a link indicating you as a source or a reference on a particular topic, the value is high. If it’s sending someone to you for more information or to buy something, it could be valuable depending on the needs of the searcher. If it’s one link of many in a directory, it may be helpful (depending on the exclusivity and trust of the directory). If it’s a link influenced by money, relationships or other less trustworthy motivations, search engines will try to find algorithmic ways to prevent it from passing value. That’s not to say it won’t help your ranking now, but over time, engines have gotten better and more efficient at measuring the quality and intention of link patterns.
Section III
Why Build Links?
As we’ve just discussed, many link building efforts in the SEO world are done to improve a site’s search engine rankings: Links as votes, as trust, as rank-building influencers, etc. There are, however, other reasons to build links as well
Gaining Direct Traffic:
Oddly enough, search engine spiders aren’t the only ones that see links to your site. Web users visiting sites can and (hopefully) do click on those links, generating direct traffic to you. Once again though, it’s worth your while to focus on quality links from relevant pages. How often have you actually clicked on a link you found on an extremely spammy, worthless page? If the original page is garbage, you assume anything it links to is probably garbage as well.
It should come as no shock that humans passively analyze page quality when assessing link value. After all, the search engines ultimately try to algorithmically reproduce the results a human would provide if they had the time to editorially rate every single page in existence.
As such, you will get higher volume and better quality direct traffic from pages that are not only popular and highly trafficked themselves, but relevant to your content.
Visibility, Branding & Influence:
What happens when every time someone looks around online for information about boats, tours or Seattle they see not only links to your site, but comments about you in every prominent blog on the subject? You become an authority in the field. By participating in the community around your niche and building content worthy of links and discussion within said community, you gain visibility, branding and influence.
How you want your image to manifest though is entirely up to you. This is just one more example where quantity may be easy to come by, but quality is what really counts. Do you want to have visibility as that guy who always has useful information, the one everybody should check out if they’re interested in Seattle boat tours? Or do you want to be the Weekly World News of your niche, always complaining of a Loch Ness-like monster in Puget Sound?
As people within (and even outside of) your community begin to recognize and respect your image and your brand, they will reference you and link to you as a resource. Links bring traffic, links bring search results, links bring passion…make your users passionate about your site.
Section IV
How Do Search Engines Measure Link Quality?
We’ve already spent a good bit of time extolling the virtues of high-quality links. That’s because search engines take great pride in their ability to have literally hundreds of algorithmic components to evaluate link quality. Some of the important factors they consider that we’ve already looked at include:
- Visibility, Status and Trust of Linking Domain (Time vs. Weekly World News)
- Semantic Value of Anchor Text (search engine optimization vs. click here)
- Location of Link in Site Structure (Deep, Natural Links vs. Shallow, Spammy Links)
In addition to these elements there are other advanced factors the engines apply when determining link value:
Location of Link on Page:
Page segmentation visually breaks a page into content blocks and—based on layout convention and actual content—determines whether or not the block contains internal navigation, ads, useful content, etc.
Image source: Microsoft Research via SEOmoz.org
Based on this structural evaluation, links from content areas are considered more valuable than links from other areas of the page. While search engines certainly are not perfect at implementing this metric, the take-away is that it’s better to have links integrated into relevant content (with good anchor text) than to have them stuck in a sidebar list or on the bottom of the page.
Relevance of Domain & Page:
Terms in your page URL and Title tags are extremely valuable when helping search engines determine the nature of your page content. As we discussed earlier, using deep page URLs that describe the page are valuable in this regard ( Search engines use semantics to determine the likelihood of content relating to search query terms.
For example, a Google search for ‘allintitle: dog & canine’ (which lists all sites with both “dog” and “canine” in the title) yields 80,300 results, whereas ‘allintitle: dog & shovel’ yields only 50 results. Similarly, ‘allinurl: dog & canine’ (which lists all sites with both terms in the actual URL) yields 15,500 results and ‘allinurl: dog & shovel’ yields zero results. While this example is painfully gratuitous, the point is clear: the engines know that if you search for ‘dog’, pages with the word canine in the URL or title are much more likely to be relevant to you than pages with the word shovel. Conversely a page with the term ‘shovel’ featured prominently in the URL may not be as reliable a source for content with the keywords dog and/or canine.
There is a whole science behind semantic indexing, but all you need to know is this: Page domains and titles that offer semantic relevance to your content convey an impression of reliability and relevance. Similarly, links to you from pages with semantically related content and or titles/URLs create consistency and relevance that the engines will reward.
Visible vs. Invisible Links:
All the links in the world won’t do you any good if the search engines cannot see them. Many sites use tactics to prevent the engines from following certain links on their pages in an effort to avoid spam.