Communication is all about interconnection. More so in this Internet Age. And it is not merely connecting to so many other people but also to your own data and other sources of information derived from various sites.
Imagine doing a research work on a certain subject and browsing through numerous books and materials in the low-tech method. You will need to put bookmarks on each material so that you will have an easier time looking up topics you are working on from the various sources you have.
Online bookmarking of relevant links does this in a very similar way. Links are virtual streets which allow us to move from one webpage to another and back again and out again to another street, and so on and so forth. It seems like a labyrinth; but search engines utilize sophisticated link analysis to determine how pages are related to one another and in what ways.
Through this complex mechanism of links, search engines are not merely capable of analyzing the popularity of a website and page based on the quantity and popularity of pages linking to them, but also metrics like trust, spam, and authority. Reliable websites tend to link to other trusted sites, while spam-filled sites obtain very few links from trusted sources.
Knowing this, users can be confident that trusted sites are authoritative sources of information. And the more trusted friends or partners you have, the more secure is your own life and career, as we know in real life. Likewise, the more popular you are in the sense of having many trusted link partners, the better chances you have to gain success in your business and social dealings online as well as in real life.
Some tips on gaining this kind of this confidence online are the following*:
Local/Topic-Specific Popularity
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.
Anchor Text
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.
Trust Rank
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 domain can result in a significant boost to this scoring metric.
Universities, government websites and non-profit organizations represent examples of high-trust domains.
Link Neighborhood
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 is wise to choose those sites you link to carefully and be equally selective with the sites you attempt to earn links from.
Freshness
Link signals tend to decay over time. Sites that were once popular often go stale, and eventually fail to earn new links. Thus, it is 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.
Social Sharing
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 algorithm, but there is no denying the rising importance of social channels.
*Source:
http://moz.com/beginners-guide-to-seo/growing-popularity-and-links