Links are the primary arteries of the Internet, the underlying connectors between different places. Links are the transporters that take you everywhere on the web. You likely came to this space via a link and are as likely to follow one out again. Links keep you going online, hopefully to places you want or need to get to.

Google created the most successful information retrieval device of all time based on sending spiders to follow each and every link they can find on each and every web document they come across. Yahoo, MSN, Ask, and all the other search databases have acquired the vast amounts of information they contain in similar fashion. Links play important roles in the ranking formulas of all search engines, especially Google, by providing numerous pieces of data for their algorithms to chew through.

How links are valued by search engines and by savvy webmasters who build sites have changed over the years however the way most web users think about links has not changed all that much. When discussing link strategies with clients, a lot of confusion comes from having two different understandings of what links are used for and how they should be used.

For most Internet users, links have always been pathways between points of interest. Link-paths might be intricate and informative but they are not necessarily seen as complex.

Search marketers however, see links a multi-dimensional universe that vaguely resembles the central nervous system. A good visual representation can be found by typing a URL into (Readers are advised to do so before continuing…) Links exist in spatial relation to the document or set of documents associated with them. Some links are internal, or contained within a unique URL. Others are external, pointing into or out from a specific document. Some links are located close to a specific page while others are two or more documents removed. Links also exist in time. Each link was placed on a certain date and will be removed at a later date. The timing of the placement and the longevity of the link have an effect on Google rankings. Lastly, and most importantly, they exist in context. Each link was originally placed for a reason and each document linked together will contain some form of information. If the information found on both pages is topically similar, the link was likely placed in order to benefit site visitors. If, on the other hand, information found on the two pages is not topically similar, the link might have been placed in order to artificially inflate Google’s perception of the site.

For search marketers and the engines they work on, links are powerful directional tools that act as indicators of a site visitor’s interests. They are used to move spiders from A – Z through a website and steer visitors towards useful information and/or specific conversion points. They are also used to gain the attention and respect of search engines. Having a number of links pointed towards your site from other topically relevant sites is a good thing. Since the earliest days of Google, link strategies have played a key role in winning strong search engine placements.

Links can give search marketers information on how a website operates. By examining the link structure of a website, most good SEOs can find points or techniques that might cause problems for search engine spiders and make suggestions for improving access. Similarly, good search marketers can show a client how live-visitors use their website. By examining data found in site logs, search marketers can often see and explain user patterns and suggest ways to reorganize the site in order to drive visitors towards conversion points.

Though links provide important tools for search engine marketers, they are amazingly difficult to understand and employ without somehow exploiting the way search algorithms are written. Learning how to acquire links without intentionally exploiting Google’s algorithm is one of the hardest facets of search engine optimization.

Building links has long been considered an important component of search engine optimization. Search engines use links to find and catalog information from one page to the next. They compare what they find on pages linked together in order to determine the topical relevancy of linked pages. Shared topicality, or context, is extremely important for strong search placements. Search engines expect that links, in all cases, should lead to useful information. As search users travel across linked pages, the search engines track how much time users spends on linked pages and the pathways they take when leaving a document.

The first commercial search engines, Alta Vista, Infoseek and Lycos tended to place weight on keywords found in the text of websites or documents, without considering the effects of links between documents. Back then, webmasters had to submit URLs to each search engine as an invitation for spiders to visit and record site information. This tedious and repetitive task is no longer necessary though hand-submission of sites to certain search directories is sometimes recommended.

In the early days, links between documents were placed by hand. A website designer had to open the source-code in Notepad and write a new line expressing the link in the appropriate place. It was a process that took a few minutes, especially when using a 14.4 or 28.8K dial-up modem.

Understanding the amount of work it took to place links, Google’s co-founders figured that each link could be valued as a positive vote. That was the original assumption behind the PageRank algorithm. When combined with traditional on-page factors such as titles, meta tags and content, link-popularity became a fairly accurate gauge of the relevance of information found on pages linked together.

As Google rapidly grew in popularity, many people working in the search engine marketing sector began using links as a means of manipulating or influencing Google’s rankings. That is where the practice of building link farms and wild networks of unrelated links came from. Over time, an expanding sub-section of the search marketing industry developed, devoting itself to building, buying or bidding for links in order to boost their clients’ chances of scoring high rankings in Google’s index.

Though links provide important tools for search engine marketers, they are amazingly difficult to understand and employ without somehow exploiting the way search algorithms are written. There is absolutely no question however, since the earliest days of Google, link strategies have played a key role in winning strong search engine placements. Learning how to build links without egregiously exploiting Google’s algorithm is one of the hardest facets of search engine optimization.

Nobody likes exploitation; especially search engineers frustrated by seeing their brilliant sorting algorithms serving spam-filled results. In order to combat link-based exploits, Google has gotten far stricter over the past two years about the types of links it considers relevant or important. While doing so however, Google and the other major search engines seek to place high value on links that are useful to site visitors, leading them to information that is likely to create a better user-experience and more loyal customers. Links that provide a positive outcome, or lead to a series of pages that can guide the user towards what they want, are highly valued in search rankings. In other words, search engineers are required to balance the bad against the good and try to weave rewards to sites with relevant links that are beneficial to site visitors.

Many webmasters and SEOs take the time to search out complimentary websites, writing personal emails requesting a link. Some send out mass-emails to tens or even hundreds of thousands of other webmasters asking for a link to their site. Some hire link-building firms to do the job for them.

Ultimately, the best way to get good incoming links is to work for them by providing extremely good content and finding ways to let others in your business or interest sector know that content exists. Other webmasters will often link to good content; the trick is finding an effective and acceptable way to present it to them.

Be very careful when hiring a company to do link building for you. The “rules” around link building can change and vary depending on the circumstance. There is no one-size-fits-all solution for link acquisition. There are a number of ways to bungle the job though.

In one well known case, a large SEO firm in California claims to have hired a link building firm that created a dense web of reciprocal links between tens of thousands of unrelated sites. The system worked well for over a year but infamously broke-down late last summer, resulting in a system-wide ban for several websites associated in the link-network. Google banned the firm, many on its client list, and many associated with the link-network. The penalty was doled out for the crime of link-farming, a practice in which a lengthy list of sites are linked together (knowingly or unknowingly) in order to artificially boost the link density Google perceives for sites within the network.

Links will continue to be an ongoing point of conversation within the search marketing community. It is a complex subject with enormous implications, regardless of where one’s opinion falls in the discussion.

Phoenix over at the SEORoundTable points out a discussion thread at the High Rankings forums that includes a quotable line from HR member Jonathan Hochman, “Looking for links is like trying to get a date. If you are desperate, nobody respectable will be interested, but if you relax and behave nicely, you’ll have plenty of success.”

The thread also contains links to a number of good articles about link building along with a lot of common sense advice. Anyone interested in thinking about link acquisition is well advised to read through it.

Last week, I had a conversation with Dirk Johnson, one of the owners of Domain Drivers. Domain Drivers uses a reciprocal linking strategy that is different, as Dirk explains it, from other recip-linking programs. Dirk’s thoughts, along with others I find digging around the web, will be the subject of another piece, very soon. I think I’ve thought about links enough for one day.