If your site's traffic is plummeting today, you're not alone. Google has unleashed a new algorithm update that targets sites that deploy spam tactics such as keyword stuffing and link schemes. In a blog entry posted yesterday, Google said the update is intended to weed out sites that "use techniques that don't benefit users, where the intent is to look for shortcuts or loopholes that would rank pages higher than they deserve to be...ranked."

For the second time this year, Google has updated its public PageRank toolbar data. PageRank is the method that Google uses to determine the importance of sites; rankings are between 0 and 10. The higher a site's PageRank rating, the more likely it is to rank prominently for competitive search phrases (assuming the site has good SEO).

The last PageRank update was this January. That update was the first since April 2010. SEOs keep track of PageRank using FireFox and Chrome plugins that display it in their browsers as a little green bar. Our home page went from a PR4 to a PR5. PageRank is determined solely using a site's inbound link profile.

If you're using Google while signed into your account, you might be seeing buttons that say �+1" next to search results. When you click the button, you'll be asked to confirm whether you want to recommend the link to your friends. As Google puts it: �The 1+ button is shorthand for 'this is pretty cool' or 'you should check this out.' Click +1 to publicly give something your stamp of approval. Your +1's can help friends, contacts, and others on the web find the best stuff when they search."

Last week, Google rolled out a major algorithm update that it says �noticeably impacts� 11.8 percent of queries. Mainly, the update affects websites whose content has been deemed as low-quality by Google's newly tweaked standards. The change is aimed at so-called content farms, which are massive databases of articles that often provide little or no value to readers and are merely a vehicle for PPC advertising.

It appears as though a Google PageRank toolbar update is underway as I write this. For those who don't know, PageRank is the method by which Google decides the importance of websites. Every site on the web is awarded a rating of between 0 and 10. Only a handful of sites are awarded a 10; Google.com, Facebook.com, CNN.com and WhiteHouse.gov are among them.

If your site has seen a decrease it traffic in the past month, it may be because of a Google algorithm update that's been dubbed �Mayday" by the search community. The change, which took effect around the beginning of May, especially impacted large sites that get a sizable amount of their traffic from so-called long-tail queries. While some sites have been impacted minimally by the change, other webmasters have been reporting near-catastrophic drops in traffic.

Matt Cutts, head of Google's webspam team, says the tweak �changes how we assess which sites are the best match for long-tail queries.� The algorithm update went through a vetting process, according to Cutts, and it is not tied to the long-awaited infrastructure change known as �Caffeine.� At Search Engine Land, former Googler Vanessa Fox noted: �Before, pages that didn't have high quality signals might still rank well if they had high relevance signals. And perhaps now, those high relevance signals don't have as much weight in ranking if the page doesn't have the right quality signals.�