A couple of years ago I was in a conference where Matt Cutts, head of Google spam team, was running a Q&A session. One question stood out; a webmaster from the audience queried Matt why his site was ranking lower than those of his competitors even though though he had over 1,000 backlinks - more than anyone else in the niche by many times over. Matt logged onto his terminal and did a quick lookup on the domain.

So what was the reason for the site's low ranking? Out of the 1,000 backlinks to the web site, only 3 were being counted!

And then it hit home with the majority of the audience. A portion of high quality backlinks is far more beneficial than a huge quantity of "spammy" links.

But what makes a quality backlink?

Many SEO folk have what I like to call binary opinions, like: "reciprocal links don't count" and so on. But, the fact is, that the Google ranking algorithm is anything but black and white, 1 or 0, but instead the sum of a wide variety of metrics used to determine the quality of any given backlink.

Continuing from the above example, It's important to realise that the ranking algorithm has been developed for many years - it's way beyond the point of identifying if a link is reciprocal and discounting the link if it is.

A huge number of metrics including: the number of inbound links, reciprocity, Class C IP structure, PageRank, on-site optimisation, link networks, position of link and relevance to name a few are used to build up a picture of the trust, authority and importance of domains and links.

So, when building backlinks, what should you be doing to make sure that majority are of high enough quality to be counted?

Relevance

Seek backlinks from web sites that are in some way related to your niche. It's natural to expect sites in the same niche to link to eachother - relevant backlinks are more likely to be counted.

The "No-Follow" Issue

Avoid "no-follow" backlinks. By their very definition, these types of links have little to no effect on search engine rankings.

Link Networks and Farms

Sourcing backlinks from some of the more obvious link farms will provide no benefit to rankings. It can be difficult and time consuming to manually figure out if any given web site is part of a link network but tell-tale signs like if a page has a huge number of outgoing links and provides little value to humans do exist.

Number of Outgoing Backlinks

The lower the better as link "juice" is divided amongst all outgoing links.

Number of Incoming Links

Generally speaking, the higher the better although as mentioned in the first paragraph of this article - volume isn't always a solid metric to use.

To quickly obtain incoming links to any given page I'd suggest using the SEOQuake Firefox extension.

You can also check the number of backlinks a site has using Yahoo site Explorer and a new site recently launched called "Open Site Explorer" from the SEO whizz kids at SEOMoz.org.

Anchor Text

Do a Google search for "click here" and the top result is Adobe. Why? Because they have a huge number of backlinks with "Click here" as the anchor.

ie: To download Adobe Acrobat reader, then "click here".

There have been numerous examples to demonstrate the power of anchor text, including a rather funny one that I won't go into about George Bush!

Simply put, if you want to rank high for a certain key phrase then you should source backlinks that contain that key phrase as the anchor text (clickable part of the link).

Crawl Regularity

By running a simple "cache:" followed by site URL search in Google you can see the last time any given site was crawled.

If it's not been crawled in the last couple of months then it might not be the best place to get a link from!

PageRank

Obviously aim for sites with a higher PageRank. For a quick way of determining what PageRank a site has then download the Google toolbar for your browser.

Site that don't have a PageRank may mean that the site is "sandboxed" or that it just has a low number of incoming links with any real quality. Either way, there's not much point spending a huge amount of effort chasing links from such pages.

Reciprocal Links

These are generally acknowledged to be less powerful than one way links which is why many webmasters have developed a secondary linking site with which they can negotiate backlink trades to their money site.

A small percentage of reciprocal linking is fine. If all your links are reciprocated then you're running the risk of getting penalised for blatantly trying to manipulate the search engine listings.

IP Addresses

If all your backlinks are from the same IP then it looks mightily contrived and your links will be discounted and you may even face some kind of penalty.

To counteract this problem some hosting companies are offering what's known as "SEO hosting" where you can host your sites across multiple Class C IP Ranges.

Domain Registration

Owning a large volume of web sites registered in the same name and having them all link to each other might have worked five years ago, but nowadays it's easily detected and you're putting yourself in grave danger of an almighty Google slap.

In Summary

When building links variance is always very important.

For instance, I know webmasters who are spending hours and hours of effort chasing what's known as "profile" backlinks for their sites - this is where you sign up for an account on a high PR web site and put a backlink in your profile page. This strategy works great at the moment but you can bet your bottom dollar that it won't be long before Google discounts these kind of links and overnight the listings of these sites will drop hugely.

It is becoming increasingly difficult to prosper from such "churn and burn" approaches to link building.

Build links from a wide variety of sources using the above metrics as a rough measure to determine their value and shield yourself from the impending slap that a lot of web sites are going to be getting over the next couple of years as the clever folks at Google further tighten the vice on discounting spammy backlinks.

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Paul McCarthy is an affiliate marketer helping people to make a full time income from home by working online. http://www.amshortcuts.com