There are many types of links with varying value and effort.

Reciprocal links (or link trading) was the traditional SEO approach.  They are relatively easy to attain, but require a link back to the link partner’s site; thus, the need for outbound-links-pages.

During mid 2006, Google changed their link algorithm and was able to detect reciprocal links.  From that time on, reciprocal links are thought to have minimal value.

One-Way links (sometimes called 3-way links) are a variation on the reciprocal link theme.  Links are still traded but instead of linking back from the target site, the link is placed on a 3rd website.  In this case, there is no need for an outbound-links-page from the target website because links are reciprocated by the 3rd party.

And, because there is no direct link reciprocation, Google is not able to detect the 3-way relationship.

Both reciprocal and one-way links typically have strong anchor text (Link Reputation).  Even though one-way links do not typically come from contextually relevant websites, their relatively low cost gives them good Organic Optimization value.

Google is actively encouraging publishers to use the rel=”nofollow” text link attribute as a method of nullifying the search engine value for each of these links.

Advertising links may be images or text.  When clicked, users are directed to the advertiser’s website through the publisher’s click tracking system.  For this reason, no direct link value is awarded to the advertiser and no search engine ranking benefit is passed.

3rd party ad serving systems are also common.  Services such as Google Adsense, use JavaScript to serve their ads.  Since search engines do not follow JavaScript code, they never see these ads and, therefore, these links do not affect rankings.

Public Relations links fall into 2 categories:

• Article Syndication
• Press Releases

Article syndication is a method of distributing articles to specialized article directories.  The articles commonly contain a small bio of the author which have links to the author’s website.  When search engines spider these articles, the backlinks have a positive contribution to rankings.

1. Google has the ability to detect reciprocal links and devalues them.
2. One-way can also be triangular links so long as each is from a different class C-IP
3. Google is getting better at detecting paid text links.  When detected, they have no SEO value.
4. Depends on quality and market size

Directory links may be either Free or Premium.

There are literally thousands of free directories.  Most have an on-line sign-up form that automatically places your link and a brief description into a category of choice.  And most are not regulated and accept any website for any reason.

Premium directories are typically fee based to justify the added labor cost associated with an editorial review.  Website must pass the directory’s terms of service and are checked for proper category preference before the listing is activated. 

During 2006, Google’s link accounting changes included directory sites.  Although most home pages of free directories maintain good PageRank, many interior link pages appear to be stripped of all PageRank value.  This change appears to have relegated these pages to Google’s supplemental index where PageRank and Link Reputation value is minimal.  In contrast premium directory interior link pages still maintain PageRank value and are considered valued links.
Advertising links are segmented into 2 groups:

• Text links
• Ad and affiliate links with tracking codes

Text links are advertising links that are just text – not images.  These links do not contain any advertising tracking code and link directly to the target site.  Because these links commonly have keyword phrases as hypertext, they pass strong Link Reputation.  When these links are placed on pages that have strong PageRank, they have very strong search engine value.

As no surprise, Google has been quite vocal about these kinds of links.  Google claims to have an automatic algorithm to detect these links and are actively nullifying their ranking contribution.  Google also encourages webmasters to report other websites they believe are either selling or participating in a “paid link” program.


 

Article directories offer these articles to other webmasters to publish on their websites.  It is through this process that articles with their backlinks find themselves on potentially hundreds of other websites.

Press releases have a similar approach, however, they are actively circulated throughout the Internet by RSS feeds.  These feeds are picked up by thousands of other websites for potential publication on their own websites.
Both Article syndication and press releases have a potential downside.  Links from public relations efforts are hard to trace and pages with these links could be considered “near duplicate content”.

Although pages with near-duplicate content may not rank well against other pages containing similar content, backlinks on these pages appear to maintain value.  As a precautionary measure Position Research recommends that article and press release pages on the author’s website be excluded from search engine indexes.

Both articles and press release link hypertext is often the name of the website or the domain name – not a keyword.  Therefore these types of links are better at passing PageRank than Link Reputation.

Editorial
Text links with strong Link Reputation found within editorial content are the best kind of links.  These links are characterized by:

• Found on pages with unique content (not near-duplicate)
• On pages with strong PageRank
• With the keyword phrase mentioned in the hypertext.
• On pages with few outbound links

For the most part, these kinds of backlinks are initiated by public relations efforts.  More public relations increase the likely that others will write editorial content and link to a target website.