Link Popularity is only one of the many factors (good content, number of pages, text, anchors, internal links, static URLs, keywords, meta tags, and many, many others) that are used in calculating your place in a search result page (ultimately, this is what all of it is about - how findable you are in a search).

PageRank (PR) is specific to Google and is a trademarked proprietary algorithm. There are many variables in the formulas used by Google, but PageRank is primarily affected by the number of links pointing to the page, the number of internal links pointing to the page within the site and the number of pages in the site.

PageRank focuses strictly on the quantity of links and is directly influenced by the PageRank of the pages that are linked.

In Google, Link Popularity puts more emphasis on the quality of links (ex. links from sites related to yours by topic or by industry rank much higher than links from non-related sites).

PageRank - as the name suggests - is specific to a web page, not to a web site. Every page on your site has a PageRank and every one is different, based mostly on your linking system. Generally - but not always - the goal is to achieve maximum PageRank on your main page, the one people hit when first entering your site.

You can check the PR of a page by installing the Google toolbar in Internet Explorer (the "official" way), a PR checker extension in Firefox, or by using one of the many online utilities, such as the one at http://www.bsleek.com/tools/link_popularity.php (which also checks Link Popularity and presence in DMOZ).

In Google only, PageRank is one of the factors that influence Link Popularity.

PageRank (PR), developed by Google founders Larry Page and Sergey Brin at Stanford University is considered to be the heart of Google's software. PageRank solves an equation of more than 500 million variables and 2 billion terms. Instead of counting direct links, PageRank interprets a link from Page A to Page B as a vote for Page B by Page A. PageRank then assesses a page's importance by the number of votes it receives and by the PR of the page which casts the vote.

There are two types of incoming links that can effectively contribute to increasing your Link Popularity:

1. Links from other sites that focus on the same keyword phrases you do. In other words, if a site that can be found in search engines by using a search phrase like "corporate cd-rom presentations" links to your site, and your site actually specializes in designing interactive media, like CDs or DVDs, then that link will help your Link Popularity. But if your site is about selling onions, then the mentioned link will be useless.
2. Links from relevant categories in major directories industry-specific directories and portals. The most important major directory is DMOZ (who feeds data to many others) and is the toughest to get in. Submission is free and there are actually people reviewing your site. The waiting times are in the months order, so my advice is submit and forget. The industry-specific directories are very important. For example, if you make interactive media, and list your site in a directory dedicated to graphic design or media under the appropriate category, then search engines like Google will pick that up as an incoming link and will increase your Link Popularity. Listing your site in such a directory is very useful to your potential visitors, and this is what Google is trying to emulate with its software. Remember, with Google and many others, there are no humans reviewing your pages, but software acting under very specific and strict rules (algorithms).

Both types of links I described above can be unilateral or reciprocal ("you link to me and I link to you").

Reciprocal links are subject of controversy and misconception today. Many people think that exchanging links with sites is the easiest way to get them, new people learning about link popularity are under the mistaken belief that they must have links that are reciprocated on their site. Still many others are saying that reciprocal links are dead and that not only you won't gain any benefit from them, but your PR (Page Rank) will decrease (your page will "leak PR", as it is said in the SEO circles). Both camps are not entirely correct. You certainly don't need to get reciprocal links, but you can if you want to. Remember, it is links pointing to your site that are the helpful ones. Links pointing from your site to other sites are wonderful to have because they help your visitors find related stuff, but if your site doesn't lend itself to linking to other sites, then by all means, don't do it. You need to do what's right for your company or hobby and your site visitors, first and foremost.

Links from sites that have nothing to do with yours will definitely not help you gain Link Popularity, but might produce a temporary boost in PR (PageRank).

If the PR (PageRank) boost is only temporary, why bother?

You should try to boost your PR (PageRank) even if temporary, because when Google sends Googlebot, its indexing robot, to spider your website, the bot is instructed not to crawl your site too deep unless it has a reasonable amount of PR (PageRank). But in order to increase your overall PR (PageRank) and, in order to have all your keywords from all your pages available for searches, you need Google to look at all of your pages, because the number of pages and the internal links affect PR (PageRank). But Google will not see your internal links and your keywords if only few pages are indexed, so you see, it's catch 22 and the best way to win this is to start working on your incoming links as early in the game as possible.

To see which pages from your website are actually indexed by the search engines, you can use the following search with the major three (Google, MSN and Yahoo!): site:www.yourdomain.com, where www.yourdomain.com is the full address of your site. There is no space between site: and the address, otherwise you are actually searching for the words site: and www.yourdomain.com.

To get a glimpse of your site's Link Popularity, use the following search with Google and MSN: link:www.yourdomain.com. Again, there is no space between link: and the address. There is a common misconception regarding this. People think that the correct format is with the space, as it might produce a lot more results. It is incorrect, as the format with the space merely looks for www.yourdomain.com and the word link:, but will not actually show you who really links to you. For Yahoo!, you'll have to use the full URL, including http://.

Please note that Google might not display all the links to your site that are stored into its database. Don't panic. It has been reported that this is reminiscence from Google's paranoia days, when the search engine's execs did not want competitors to figure out the way they track Link Popularity.

As a word of caution, please do not waste your money on submitting your sites to "hundreds of nothing sites". Free-For-All sites are not considered quality links today. This approach might have worked years ago, but search engines are constantly trying to stop any activity they consider as spamming, designed to artificially inflate numbers. This is actually a great thing, as it keeps the internet a fair and happy place.

Two more words of caution:

1. If you read SEO (Search Engine Optimization) related articles, please make sure you read stuff as recent as possible, as things change.
2. Major search engines, especially Google, keep their algorithms (rules) in deep secret. Therefore, you'll probably wonder why you are reading so many different opinions, sometimes conflicting. The answer is simple, because little is actually known to the public about the deep inner workings of a search engine.

In general, there's no need for the average site to obsess over link popularity. Contrary to popular belief, link popularity constitutes only a portion of most search engines' ranking algorithms. Arguably, Google places more emphasis than most other engines on incoming links at this point in time. How much these actually boost a site's ranking is debatable and truly depends on the site. It also depends on the words that are placed in the anchor text (the clickable portion of a text link). From my personal experience, just a few highly relevant links with strong anchor text can go a long way towards link popularity for many sites.


About The Author
Andrei Smith co-owns bsleek ( http://www.bsleek.com ) - a site that specializes in web hosting, design, promotional items, printing, CD Presentations and more. Andrei is on the Board of Consultants for Daterade.com and has amassed an extensive technical knowledge and experience through his career as the CIO for a major travel management company and through his past careers in military research, data acquisition and aerospace engineering.