Put simply, to search engines such as Google that crawl and index the World Wide Web, links are the streets between the pages. Using sophisticated link analysis the search engines can discover and understand how pages are related to each other and in what ways. In general the more links pointing to a particular page the more popular the page is thought to be.
A considerable portion of a search engines algorithm is the analysis of, the number of, type of, and quality of links pointing to your website. Through these links search engines can analyse the popularity of a site and gain an understanding of what your site is about by reading the anchor text using in a link.
Because of the focus on links, growing a wide and varied link profile is essential in gaining traction in climbing the rankings in search engines and in any SEO campaign one of the most important tasks is link building.
Link Signals used by search engines
Before starting a link building campaign its important to understand the elements of how links are used by search engines and how these elements factor into the weighting of links by the search engine algorithms. We do not know all the attributes used by the search engines but through analysis of patent applications, hands on testing and experience we can draw some educated assumptions:
Global Popularity
The more popular and important a website is the more weight links from such a site carry. For example a link from the BBC website will be more powerful than a link from a brand new blog. This is down to the trust and authority the BBC website has built up in the search engines over many years. This is an extreme example but does illustrate the point of global popularity.
Topic Specific Popularity
Getting a link from a website in the same ‘niche’ as your own website is far more important than from a random website.
Anchor Text
One of the strongest signals the search engines use in a ranking a website is anchor text. If many links point to a page with certain keywords there is a very good chance of ranking well for those targeted keywords.
Trust Rank
In order to get rid of massive amounts of spam search engines have intelligent systems for measuring website trust, so depending on how much trust a website of which you are getting a link from has a bearing on the benefit you get from this link.
