Anyone who understands SEO also understands that obtaining good backlinks (links to your site from other sites) is a critical success factor if you want a site to rank well. That is because each link to a site is essentially a popularity vote for the site.
At one time, “a link was a link” and every link to a site scored equally well and added to the ranking ability for the site. Today, the quality of a link is a very important factor, especially with Google. There are certain inheritance factors that are passed from the linking site to the receiving site with each link. This is commonly referred to as “link juice” by SEO professionals.
Each link to a site is recorded and rated by several factors, many of which are only known to Google. The more link juice that is passed, the more the link will influence the receiving site’s ranking ability. Google actively discounts or disregards the value of some links, which means that they are essentially useless for SEO purposes. They may perhaps drive some traffic, but they will not help a site achieve higher rankings.
Here is how to determine if a backlink is a good quality link.
1. Does the page on which the link appears display a PageRank value when using the Google toolbar?
While PageRank itself has very little influence on a site’s ability to rank well, it can reveal if the page on which the link appears is penalized or has not been indexed. Google updates the PageRank values for their toolbar approximately every three months, so a page that is older than three months that does not display a PageRank value (from 0 to 10) may have a problem. If the PageRank value is grayed-out, then either the page has been penalized, the page has not been indexed, or the page was posted since the last PageRank update.
If you are seeking a link from a site it is important to check the PageRank of the page the link will appear on. The PageRank of the home page for the site is irrelevant. The only PageRank value that gets passed is the value of the page where the link appears. If the home page has a PageRank of 5, but all of the site’s inner pages where links appear are gray-barred, the value of the link from an inner page may be zero.
2. Does the linking site contain information that matches the theme for your site?
Some of the most effective links are natural links. Google prefers natural links over other types of links. One of the factors for identifying a natural link is that it should be a link leading to a web page from a web site in a related industry. Each major search engine keeps track of the themes for a site. The themes are the keyword search phrases for which a site ranks well. If you have an automotive site, some of the best natural links that you can obtain are from other automotive sites.
3. How well does the linking site rank in search results pages that for the search phrases you have targeted for your site?
Links from sites that already rank well for your targeted search phrases may have a strong influence on reinforcing the theme for your page. These types of links can be very hard to obtain, but can be golden if you can get them.
Links from an authority site, which is a site that tends to have the best information in an industry, will likely count much more than a links from small, unknown sites that seldom shows up in search results.
4. Where is the link located on the page?
This is also a strong factor in forming natural links. A natural link is a link that appears within the text of an article or in the content on a page. These are the types of links that are commonly found on news pages that link to other pages that further explain details about the keyword phrase in the hyperlink text.
If the link is located in a footer or sidebar along with other links, it may be discounted heavily or ignored. These types of links are commonly paid links, which Google has been on a vendetta to penalize for several years. If a link looks like it is a paid link, it will probably be discounted or ignored by Google. Yahoo and Bing have not taken a strong position on the issue of paid links, but Google has.
5. How many links are on a page?
The amount of PageRank that is passed from a linking page to another page is determined in part by how many links appear on a page. PageRank is diluted by dividing it by the number of links on a page. As a general rule, a page linking to your page should not contain any more than 10 or 20 outbound links. We use a rule of no more than 50 total links (including internal navigation) per page. The fewer the number of outbound links on a linking page, the greater the amount of link juice that gets passes to each page.
6. Does either the page or the hyperlink code contain a nofollow value?
If the page uses a “nofollow” attribute in either a meta tag in the head section of the page code or in the hyperlink itself, the links will not pass any link juice. Google, Yahoo and Bing each recognize these attributes.
A nofollow meta tag in the head section of HTML/XHTML code looks like this:
<meta name="robots" content="noindex,follow" />
A nofollow attribute added to a hyperlink looks like this:
<a href="http://www.anothersite.com" rel="nofollow">Link Text</a>
Many sites, including some forums and most blogs, add a nofollow attribute to all outbound links in comments or member signatures. You should learn enough HTML to be able to view a web page’s code to look for these attributes. Unless a plugin is installed that allows links to pass link juice, all WordPress blogs add the nofollow attribute to link in comments by default.
This information should help you to determine whether or not the backlinks you seek for your site will help your site to perform better with search engines. It is usually a good idea to avoid spending your time obtaining links that return little value, and focus more on identifying links that do. With today’s search engine ranking algorithms, a few dozen high quality backlinks can be worth much more than thousands of poor quality links.