Used by search engines before embarking on a link building effort, it’s critical to understand the elements of a link used by the search engines as well as how those elements factor into the weighting of links in the algorithms. Search engines use links in many different ways. While we don’t know the entire link attributes measured by the engines, through analysis of patent applications, years of experience and hands-on testing, we can draw some intelligent assumptions that hold up in the real world. Below is a list of notable factors worthy of consideration. These signals, and many more, are considered by professional SEOs when measuring link value and a site’s link profile.
The more popular and important a site is, the more links from that site matter. A site like Wikipedia has literally 1000’s of diverse sites linking to it, which means it’s probably a popular and important site. To earn trust and authority with the engines, you’ll need the help of other link partners “The more popular, the better.”
The concept of “local” popularity, first pioneered by the Teoma search engine, suggests that links from sites within a topic-specific community matter more than links from general or off-topic sites. For example, if your website sells dog houses, earning links from the Society of Dog Breeders matters much more than earning links from an off-topic, roller skating site.
One of the strongest signals the engines use in rankings is anchor text. If dozens of links point to a page with the right keywords, that page has a very good probability of ranking well for the targeted phrase in that anchor text. You can see examples of this in action with searches like “click here“, where many results rank solely due to the anchor text of inbound links.
It’s no surprise that the Internet contains massive amounts of spam. Some estimate as much as 60% of the web’s pages are spam. In order to weed out this irrelevant content, search engines use systems for measuring trust, many of which are based on the link graph. Earning links from highly trusted domains can result in a significant boost to this scoring metric. Universities, government websites and non-profit organizations represent examples of high-trust domains.
Spam links often go both ways. A website that links to spam is likely spam itself, and in turn often has many spam sites linking back to it. By looking at the totality of these links in aggregate, search engines can understand the “link neighborhood” your website exists in. Thus, it’s wise to choose those sites you link to carefully and be equally selective with the sites you attempt to earn links from.
Link signals tend to decay over time. Sites that were once popular often go stale, and eventually fail to earn new links. Thus, it’s important not only to earn links to your website, but also to continue to earn additional links over time. Commonly referred to as “FreshRank,” search engines use the freshness signals of links to judge current popularity and relevance.
The last few years has seen an explosion in the amount of content shared through social services such as Facebook, Twitter and Google+. Although search engines treat socially shared links differently than other types of links, they notice them nonetheless. There is much debate among search professionals as to how exactly search engines factor social link signals into their algorithm, but there is no denying the rising importance of social channels.
Link building is an art. It’s almost always the most challenging part of an SEO’s job, but also the one most critical to success. Link building requires creativity, hustle, and often, a budget. No two link building campaigns are the same, and the way you choose to build links depends as much upon your website as it does your personality. Below are three basic types of link acquisition.
- “Natural” Editorial LinksLinks that are given naturally by sites and pages that want to link to your content or company. These links require no specific action from the SEO, other than the creation of worthy material (great content) and the ability to create awareness about it.
- Manual “Outreach” Link BuildingThe SEO creates these links by emailing bloggers for links, submitting sites to directories, or paying for listings of any kind. The SEO often creates a value proposition by explaining to the link target why creating the link is in their best interest. Examples include filling out forms for submissions to a website award program or convincing a professor that your resource is worthy of inclusion on the public syllabus.
- Self-Created, Non-EditorialHundreds of thousands of websites offer any visitor the opportunity to create links through guest book signings, forum signatures, blog comments, or user profiles. These links offer the lowest value, but can, in aggregate, still have an impact for some sites. In general, search engines continue to devalue most of these types of links, and have been known to penalize sites that pursue these links aggressively. Today, these types of links are often considered spammy and should be pursued with caution.