Google is the Web's most popular search engine, powering not only the popular Google.com Website, but also Yahoo! and AOL. Being listed in Google is very important, and being listed highly in Google can bring great benefit to your site.
However, there are many myths about how Google works and, while fairly harmless in themselves, these myths tend to allow people to draw incorrect conclusions about how Google works. The purpose of this article is to correct the most popular Google myths.
Myth #1: The Higher Your Google PageRank (PR), the Higher You'll be in the Search Results Listing
This myth is frequent, and is the source of many complaints. People often notice that a site with a lower PageRank than theirs is listed above them, and get upset. While pages with a higher PageRank do tend to rank better, it is perfectly normal for a site to appear higher in the results listings even though it has a lower PageRank than competing pages.
To explain this concept without going into too much technical detail, it is best to think of PageRank as being comprised of two different values. One value, which we'll call "General PageRank" is nothing more than the weighting given to the links on your page. This is also the value shown in the Google Toolbar. This value is used to calculate the weighting of the links leaving your page, not your search position.
The other value we'll call "Specific PageRank." You see, if PageRank equated to search engine results rank then Yahoo, the site with the highest PR, would be listed #1 for every search result. Obviously, that wouldn't be useful, so what Google does is examine the context of your incoming links, and only those links that relate to the specific keyword being searched on will help you achieve a higher ranking for that keyword. It's very possible for a site with a lower PageRank to in fact have more on-topic incoming links than a site with a higher PageRank, in which case the site with a lower PageRank will be listed above its competitor in the search results for that term.
PageRank aside, there are also other factors that contribute Google search results -- though PageRank remains the dominant one.
Myth #2: The Google Toolbar will List Your Actual PageRank
When Google created their toolbar it was a boon for many Webmasters as this was the first time we got to see any value related to our PageRank. However, the toolbar has also caused some confusion.
The toolbar does not show your actual PageRank, only an approximation of it. It gives you an integer rank on a scale from 1-10. We do not know exactly what the various integers correspond to, but we're sure that their curve is similar to an exponential curve with each new "plateau" being harder to reach than the last. I have personally done some research into this, and so far the results point to an exponential base of 4. So a PR of 6 is 4 times as difficult to attain as a PR of 5.
The exponential base is important because it illustrates how broad a range of pages can be assigned a particular PR value. The difference between a high PR of 6, and a low PR of 6, could be hundreds or thousands of links. So if your PR as reported by the toolbar increases or drops, it's important to remember that it could be the result of a small change, or a large change. Additionally, it's possible to lose or gain links and see no change in your reported PageRank.
The other issue with the toolbar has to do with the fact that sometimes the PageRank it displays is only a guess. People will often notice pages on Geocities or another free hosting provider having a high PageRank. This is because when Google hasn't spidered a page, but has spidered the root domain, the toolbar will guess a PageRank based on the value of the root domain. Therefor it's common to see pages on Geocities with a PR of 6 or 7. The PageRank does not equate in any way to a high Google listing, in fact in this case it indicates the opposite: that the page isn't even in Google. Once Google spiders the page, it will be assigned a more appropriate (and usually lower) PageRank.
Myth # 3: PageRank is a Value Based on the Number of Incoming Links to Your Site
This myth is a frequent source of incorrect assumptions about Google. People will often see that a site with fewer incoming links than their own site has a higher PageRank, and assume that PageRank is not based on incoming links.
The fact is that PageRank is based on incoming links, but not just on the number of them. Instead PageRank is based on the value of your incoming links. To find the value of an incoming link look at the PR of the source page, and divide it by the number of links on that page. It's very possible to get a PR of 6 or 7 from only a handful of incoming links if your links are "weighty" enough.
Also remember that for PageRank calculations every page is an island. Google does not calculate PageRank on a site-wide basis -- so internal links between your pages do count. This is very important, as instituting a proper structure for your internal links can drastically improve your rankings.
Myth # 4: Searching for Incoming Links on Google Using "link:" will Show you all Your Backwards Links
Similar to Myth #3, people will sometimes look for backwards links to a site on Google and fine none, but if the site does have a PR listed and it is in Google's cache, they know that the toolbar isn't just guessing.
The reason for this is that Google does not list all the links that it knows about, only those that contribute above a certain amount of PageRank. This is especially evident in a brand new site. By default, all pages in Google have a minimum PR. So even a page without any incoming links has a PR value, albeit a small one. If you have a brand new site with 20 or 30 pages, all of which Google has spidered, but you have no incoming links from other sites, then your pages will still have a PageRank resulting from these internal links. As your home page is likely linked to from every page on your site, it might even get a PageRank of up to 1 or 2 from all these little boosts. However, in this situation searching for incoming links will likely yield 0 results.
You can also see this happening on pages that have been around for awhile. For instance, this page has 0 incoming links listed in Google, yet it has a PageRank of 3. We can see that Google has spidered it by checking its cache, so the PageRank is not a guess. We also know that Google has spidered this page, again by checking its cache. Therefore, we can be sure that Google knows of at least 1 link to the page in question, both by its listed PR, and the fact that Google has spidered a page that links to it.
However, if you look at the DMOZ.org page with the Google Toolbar installed, you'll notice the page has a PR of 0, which is very low. Furthermore, if you count the number of links on the page, you'll notice it has over 20. So you're dividing a very low PR among over 20 links. Thus each link carries very little weight, so Google doesn't list these links when you search for them. However, Google does count the links, which is why the page in question has a PR listed.
It's very important to remember how Google lists incoming links. Often, people see their number of incoming links drop, and they think they have lost those links. In reality, the linking page could have lost some weight and consequentially, the links might have dropped below the value threshold that's required in order for links to be listed. Or the linking page could have added more links, causing each link's share of the weight to be lower, and again causing the link to drop below the value threshold. In either case the link is still counted, it just isn't listed.
Why does Google do this? Perhaps the answer has to do with technical limitations. If the average number of links per page is 20 then Google would have to deal with over 60 billion links, which might create an index that was too large to be publicly searchable.
Myth #5: Being Listed in the Open Directory Project Gives you a Special PageRank Bonus
Google uses Open Directory Project (DMOZ.org), to power its directory. Coupling that fact with the observation that sites listed in DMOZ often get decent and inexplicable PageRank boosts, has lead many to conclude that Google gives a special bonus to sites listed in DMOZ. This is simply not true.
The only bonus gained from being in DMOZ is the same bonus a site would achieve from being linked to by any other site. However, DMOZ data is used by hundreds of sites. The biggest user of DMOZ data is Google, but it is also used by thousands of other sites. The links from these sites are often too weak to be listed in a link search, but Google does crawl them, and the links do count. So if you're listed in DMOZ, you're actually gaining the benefits of hundreds of lightly-weighted incoming links, and when you add all those up, the total can amount to a decent PageRank boost.
There are two other benefits you can gain by being listed in DMOZ. For one, your directory description will appear with Google search result listings, which may increase the likelihood of someone clicking on your link. The other benefit is that, as Google does crawl DMOZ, being listed there will ensure that you're also listed in Google. However, as it's so easy to be listed in Google, this benefit is slight at best.
Myth #6: Being Listed in Yahoo! Gives you a Special PageRank Bonus
This myth evolved much in the same was as Myth #5. Google has been partnered with Yahoo! for a number of years by providing secondary search results, and just recently (Fall, 2002), Yahoo! started using Google to provide primary search results.
Because Yahoo! uses Google, many have assumed that Google also uses Yahoo!, which is not the case. The only PageRank you will gain from being listed in Yahoo! is the same as the PR you'd gain from any other site of equivalent weight. However, some people achieve a larger-than-normal boost from their listing in Yahoo!, which again leads to this incorrect conclusion.
The fact is that being listed in Yahoo!'s main directory will often get you into regional directories, so, much like DMOZ, one Yahoo! listing can result in multiple links. These links are often weak in nature so they may not show up in a link search, but they are there -- and Google knows about them.
Additionally, once you're listed in any search engine or directory you have an increased chance of someone finding your site, liking it, and adding a link to it from their own site. As such, being listed in Yahoo! could result in you receiving links from elsewhere -- links whose weight is too low to list, but which do contribute to your PageRank.
Myth #7: Google Uses Meta Tags to Rank Your Site
This myth is left over from the days when most search engines used meta tags. However, Google has never used them. This fact may be contested by some people, so I wouldn't post it without proof.
To prove to yourself that Google doesn't use meta tags, put words into your meta tags that do not appear elsewhere on your page. Then, using an advanced search, search for those words while limiting the results to your domain only. You can try this on any search engine -- and if results appear, you'll know that engine uses meta tags. If no results are displayed, then you know meta tags are not used. It is important, though, that the words only appear in your meta tags and no where else on your page.
Google can sometimes use the meta description tag to create an abstract for your site, so it may be useful to you if your home page is primarily composed of graphics. However, do not expect it to increase your rank.
Myth #8: Google Will Not Index Dynamic Pages
Some search engines have, in the past, had problems with dynamic pages, that is, pages that use a query string. This was not due to any technical limitation, but rather, because search engines knew that it was possible to create a set of an infinite amount of dynamic pages, or they could create an endless loop. In either case, the search engines did not want their crawlers to be caught spidering endless numbers of dynamically generated pages.
Google is a newer search engine, and has never had a problem with query strings. However, some dynamic pages can still throw Google for a loop.
Some shopping carts or forums store session information in the URL when cookies are unable to be written. This effectively kills search engines like Google because search engines key their indexes with URLs, and when you put session information in the URL, that URL will change constantly. This is especially true as Google uses multiple IP addresses to crawl the Web, so each crawler will see a different URL on your site, which basically results in those pages not being listed. It is important that if you use such software, you amend it so that if cookies are unable to be written, the software simply does not track session information.
So, you don't need to use search engine-friendly URLs to be listed in Google. However, these URLs do have other benefits, such as hiding what server side technology you use (so that you may change it seamlessly later), and they are more people-friendly. Additionally, while Google can spider dynamic pages, it may limit the amount of dynamic pages it spiders from one particular site. Your best bet for a good ranking is to use search-engine friendly URLs.
Myth # 9: Google Will Not List Your Site, or Penalize it, if you use Popups
This is a relatively minor myth but it still pops up (pun intended) every once in a while. Google has an advertising program called Adwords, and one of their policies is that they do not allow sites that use popup windows to participate in this program.
Myth # 10: Google will Penalize you if You're Linked to by a Link Farm
Google has policies against the use of artificial means to increase your PageRank, which specifically include things like joining a link farm. There are sites or services out there that set up automatic link exchanges to increase your PageRank. The links are usually hidden from people through the use of CSS, and either making the text the same color as the background, or by putting the links in an invisible layer. As search engines don't render CSS, they will see the hidden links and thus count them when calculating your link popularity.
However, despite all this, Google will not penalize you for being linked to by a link farm. After all, you have no control over which sites links to you, so it wouldn't be fair to penalize site owners on this basis. Additionally, link farms often have low PageRanks and a high number of outgoing links, so each link will contribute only a very small amount to your total PageRank -- and thus this method of abuse is not very effective.
Even so, Google can punish you if you link to a linkfarm from your site, or otherwise put hidden links in your pages. So the simple truth is that you can be punished for what you do to your own site, but not for getting linked by another site.