Link popularity has emerged as one of the buzzwords in the search engine optimization community. This was aided in large part by its introduction as a key factor in Google's web page ranking algorithms. In fact, the term 'link popularity' has often been used interchangeably with the search engine's branded version, called PageRankT.
The underlying theory is that, if other (high-quality) sites are linking to yours, then your web site must be important and, therefore, deserves a higher ranking than it would otherwise have. The more quality, relevant incoming links to your page, the higher it will rank.
One might argue that not all search engines factor in or give more weight to link popularity in their ranking algorithms, so why bother? Well, Google does, and since it is possibly the world's number one search engine, it is quite understandable why link building has become an essential search engine optimization strategy for many webmasters.
And there are other reasons why building link popularity should be a part of your SEO strategy too.
* Web users visiting other sites will be able to find your site too (more traffic for you)
* Links serve as trails for search engine spiders (robots) to follow, find and index or re-index your site (getting linked to a site that's already been indexed increases your site's chances of being visited by the spiders too)
But before you even start link building, it is important that you optimize your internal linkages first.
* Make sure that your site is 'crawlable.'
o Pages that spiders can't find won't get indexed, even if they've been optimized
o Avoid URLs with long numbers because Google won't spider any URL that looks like it has a Session ID in it
o Make sure your pages always link out (to your site's other pages)
o Structure the internal links so that targeted search terms are reinforced
* Use link/anchor text (the text that is clicked on when clicking on a link)
o Syntax: link text
o target page's main search term/topic should be included in the link text
o don't use identical link text for every link that links to a page
* Conserve/Distribute Link Weight
o more important pages should be linked to more often within the site
o SLA pages and the like need not have a link from each page
o minimize links to external sites