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Growing Popularity and Links
For search engines that crawl the vast metropolis of the web, links are the streets between pages. Using sophisticated link analysis, the engines can discover how pages are related to each other and in what ways.
Since the late 1990s, search engines have treated links as votes for popularity and importance in the ongoing democratic opinion poll of the web. The engines themselves have refined the use of link data to a fine art, and use complex algorithms to perform nuanced evaluations of sites and pages based on this information.
Links aren't everything in SEO, but search professionals attribute a large portion of the engines' algorithms to link-related factors. Through links, engines can not only analyze the popularity websites and pages based on the number and popularity of pages linking to them, but also metrics like trust, spam, and authority. Trustworthy sites tend to link to other trusted sites, while spammy sites receive very few links from trusted sources. Authority models, like those postulated in the suggestion, that links are a very good way of identifying expert documents on a given subject.
How do search engines assign values to links? To answer this, we need to explore the individual elements of a link and look at how the search engines assess these elements. We don't fully understand the proprietary metrics that search engines use, but 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 more are considered by professional SEOs when measuring link value and a site's link profile. You may also enjoy some further on the Moz Blog reading about search engine valuation of links.
The more popular and important a site is, the more links from that site matter. A site like Wikipedia has thousands 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, a link from the Society of Dog Breeders matters much more than one from a site about roller skating.
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, 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 these links in the aggregate, search engines can understand the "link neighborhood" in which your website exists. 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 to continue earning 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 have 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 algorithms, but there is no denying the rising importance of social channels.
The years 2011-2012 saw a huge rise in social sharing and its effects on search. Google, in particular, began to incorporate a huge number of social signals into its search results. This involves serving personalized results to logged-in users that include content shared by the searcher's social circle (Facebook, Twitter, and others). These results might not always appear in the top ten but are undoubtedly promoted due to this social influence.
The potential power of this shift towards social for search marketers is huge. Someone with a large social circle, who shares a lot of material, is more likely to see that material (and her face) promoted in search results. For publishers, it's beneficial to have your content shared by these highly influential folks with large social followings. For Google searches, this is especially true of content shared on Google+.
In a word: no. Although there is evidence that social shares such as Tweets, Likes, and Plusses affect rankings, at this time links are considered a far superior and more lasting way to promote the popularity of your content than any other method.
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.
Chuck Reynolds
Contributor
