Did you know that the little green bar in your Google toolbar is always late? Do you ever wonder why your brand new site remained at a PR 0 after the last PR update even though you acquired a handful of PR heavy backlinks just before the update occurred? "Visual" PR (the green bar on your Google toolbar) always has a lag. What do I mean by a lag? I mean that the backlink data used to calculate your visual PR is anywhere from one to ten weeks old. So for example, if the PR update occurs on January 1st, 2005, chances are that the backlink data being used update the PR value(s) will be from somewhere between October 15th to December 25th (give or take a handful of days). Anyone familiar with astronomy will understand the following analogy:Visual PR is akin to light from the sun or from a distant star. It provides you with a glimpse into the past because the information that you are receiving is dated. Just as the light from a distant star is millions of years old when we see it here on earth, the PR rank on your little green bar is weeks old when it finally gets "updated" on the toolbar.This PR lag is the primary reason for the overabundance of posts like:"50 backlinks, but no PR…Why?""I've been building up my backlinks for a while, but no PR…Why?"I've been busting my butt looking for inbound links, but no PR…Why?"Backlinks but not PR. My health is failing and my hair is falling out…Why?Relax! It is important to understand a couple of basic ideas when undertaking the difficult task of optimizing a website for Google:1)The world does not revolve around you (in other words, Google doesn't hate you…you're just doing something wrong or you need to be more patient).2)PR and SERPs position (Search Engine Results Position) are not directly related. You do not need an extremely high PR in order to achieve favorable SERPs, and on the flip side, havng an extremely high PR will not guarantee favorable SERPs.3)PR is not the end all be all in terms of gauging the "potency" or "relevancy" of a particular URL. In fact, visual PR has absolutely nothing to do with relevancy. It is simply a measure of the quantity and quality of your backlinks irregardless of relevancy. Also, while visual PR does measure the "potency" of your site's backlinks, there are other critical factors that must be considered.4)The "lag" associated with PR makes it that much less accurate in terms of gauging the "potency" of a particular URL.Before moving on, let me define some of the terms that I am using in this article, so that there is no confusion. We've already defined PR "lag, but there are few other terms that are worthy of mention:Visual PR- refers to the value reflected in the green bar located on the Google toolbar. It is a visual representation that ranges from 0 to 10. It is important to note that visual PR is not used in Google's ranking algorithm. Instead, a different and more complex PR calculation (that is not available to the public) is used as part of Google's SERP algorithm.Potency- refers to the ranking power of a particular URL or a particular backlink from that URL. For example, a page on Amazon.com is much more potent (in terms of ranking well in Google) than a link from bobby's-chicken-ribs-shack.com. O.K. now that we've clarified some of these terms, let get on with the meat of this article. Too many SEO /webmasters are unaware of the nature of visual PR and its relation to SERPs. This can lead to a lot of confusion in the current SEO climate. How? Well for starters, many webmasters refuse to give a backlink to a site that has a PR of 0. Because of the fact that PR updates seem to be coming around only once every three months, and because these PR updates can have a lag of as much as two months, it is entirely possible for a new site to not acquire any visual PR for up to 5 months! While this might be an extreme scenario, the point is still valid. It is not wise to measure the worthiness of a site based on only its visual PR value. Just because a site has a PR of 0 doesn't mean that it's banned, penalized, or lacking in terms of SERPs potency.So what else should a site be measured by? For starters, it's always a good idea to check a site's backlink info. Not just in Google, but also in Yahoo or MSN or Marketleap. It is a fairly well known fact that Google's backlink sample is purposely incomplete, so make sure to check the more accurate samples offered by the alternative sources mentioned. Once you've begun to take a look at the backlink sample for the site in question, it's a good idea to check the quality and relevance of the backlinks. Does DMOZ show up? Are there a lot of quality backlinks from reputable sites? Are there a lot of backlinks from sites with relevant content? Are all of the backlinks from the same domain, or do a variety of domains show up in the backlink sample?What else should be taken into account? In a word…content! It is fairly easy to judge the potential or legitimacy of a new site by looking at the way in which the visual content is presented. Is the site a link farm with no original content? Are there a bunch of spammy affiliate links or irrelevant ads? Does the site have fresh content updated daily? Is the site design clean and the navigation smooth? All of these factors will help determine whether or not exchanging links, acquiring a backlink, or giving a backlink is worth your while. Remember that PR 0 weakling today could end up being a PR 7 monster in a short while.So far, we've covered to important aspects relating to PR lag. First and foremost, it is important for webmasters to understand the nature visual PR and the updating of visual PR. Secondly (but just as important), webmasters should take the PR lag into account and understand that just because site has little or no PR doesn't mean that it has no value.Let's move onto some other quick points to ponder:1)PR lag has nothing to do with theoretical "Sandbox". PR lag is associated with visual PR while the "Sandbox" theory is associated with SERPs. Remember that visual PR is not a part of SERPs calculation.2)PR lag does not necessarily apply to the internal PR calculations used for the SERPs algorithm. Often, the effect of a new backlink can make an impact on SERPs almost immediately. It depends on the potency of the backlink, the current position within SERPs, and the level of competition for the given search term in question.Note: This entire statement is opinion. It is based purely on circumstantial evidence. Do not take this as a statement of pure fact! Feel free to strongly disagree.3)It is somewhat difficult to accurately gauge the lag for a given PR update. It used to be much easier when PR updates occurred every 3-6 weeks. There is a thread discussing how long of a lag there was on the last PR update (October 7th). You can view that thread here:http://www.seoproject.com/forum/index.php?board=7;action=display;threadid=199;start=154)PR updates are not directly related to algo tweaks or SERPs changes. Google is now updating SERPs on a daily basis and algo tweaks come and go so it is pointless to try and predict them. Your rankings will ebb and flow from time to time, but if your optimization strategy is sound and you work on building content your rankings will tend to improve over time.In the end, the bottom line is that visual PR should not be the focus of your optimization efforts. There are a lot of other factors that are much more influential on Google SERPs. Don't spend all of your time fretting about your precious PR values. Spend more time developing content and acquiring potent and relevant content. Visual PR may come and go, but a sound optimization strategy that factors in PR, on-page factors, content, design, and navigation will provide long term results. I hope this helps.