SEO Crunch

There is no denying the importance of link building. From an SEO perspective, the value of links is determined by a number of factors, each of which is believed to have more or less value, depending on the SEO expert you believe.

However, no two links are of the same value, so will outline and discuss the top ten factors that determine the value of links to your web site.

1. Domain authority and quality of backlinks.
The number and quality of backlinks to the linking site is significant. A site that itself has a large number of inbound links with strong authority and relevance to its content will have far more value in raising the target site’s own authority and ranking. Links from sites with few inbound links or even many low quality inbounds has comparatively less value.

2. Importance of anchor text.
Anchor text refers to the words that appear in a text link. The more relevant the anchor is to your site’s content, the more value it will have. Perhaps even more important is how popular the anchor is as a phrase in search engine queries. For example, the phrase “Home Insurance” gets far more queries than “Home Design”. You can check the relative number of search queries a given phrase gets by using Google Trends.

3. Page authority and number of inbound links.
Like domain authority, page authority as measured by the number and quality of inbound links to that page also plays an important role in determining the value a link on it can impart to the target URL. This is one reason you want to get links to “inner” pages on your web site, not just the home page; it will in turn give your pages more authority, which helps to improve your pages’ search rankings.

4. Number of outbound links on a page.
Link Juice as it has been called, is passed from one page to another. This can be used to increase the authority of internal site pages or shared externally in the case of outbound links. However, since a given page has only so much juice to impart, a page with a large number of outbound links will have less value with one fewer links; less is more in this case.

5. Total number of links on a page.
As with the number of outbound links, the total number of links is also of significance. It is believed that spiders will not index more than about 100 total links on any given page, although this is a highly speculative estimate. One thing to give attention to on your site is how many internal links you have on each page; you wouldn’t want to link to every page on your own site, especially if you have hundreds or thousands of pages. Keep your page-level navigational links to high level or category pages only and use a site map instead of trying to link to all your pages in the site wide navigation structure.

6. Age of domain name.
The value of a domain’s age is another highly debated topic among SEO circles. Most agree that domain age, in and of itself, has little or no importance in SE algorithms. However, since an aged domain will tend to have more indexed content and inbound links, they can impart more link value than newer sites, which often have less indexed content and lower quantity and/or quality of inbounds.

7. Relevant authority and ranking of a page.
The SE rankings a page obtains will also play a large role in determining the value it imparts to a target URL. For example, a page about “Home Insurance” that has strong SERPs for that anchor has excellent value to a target URL that also contains content relevant to “Home Insurance”. A link from a page about “Waste Removal” will have very little value to the same target URL, regardless of its SERPs and authority with search engines.

8. Links from penalized pages.
A page which has been penalized by SEs, meaning that the page doesn’t even rank for its own title tag or very similar query, has no value to a target URL. Enough said.

9. Text links versus image links.
Text links with quality anchor text are more likely to impart value to the target URL than an image, even if the image includes the same anchor text in the “alt” attribute. To what degree exactly this statement is true, depends on the SEO expert you ask, but there is little agreement that text links have some degree more value than image links.

10. Links to pages excluded by robots.txt
An inbound link to a page on your web site which you have specifically excluded using robots.txt will have no value, assuming that robots.txt is honored and therefore will not be spidered.

Additional Links

Link Value Factors - Wiep.net

Search Engine Ranking Factors - SEOmoz.org