1. The basics
Google's order of results is automatically
determined by several factors, including our PageRank algorithm. Please
check out our "Why
Use Google" page for more details. Due to the
nature of our business and our interest in protecting the integrity of our
search results, this is the only information we make available to the
public about our ranking system.
2. Why does my page's rank keep changing?
We update our index every four weeks. Each time we
update our database of web pages, our index invariably shifts: We find new
sites, we lose some sites, and sites ranking may change. Your rank
naturally will be affected by changes in the ranking of other sites. You
can be assured that no one at Google has hand adjusted the results to
decrease the ranking of one site or increase the ranking of another.
Google's order of results is automatically determined by several factors,
including our PageRank algorithm. Please check out our "Why
Use Google" page for more information on how
this works.
You may want to check and see if the number of other
sites linking to your URL has changed. This is the single biggest factor
in determining what sites are indexed by Google, as we find most pages
when our robots crawl the web and jump from page to page via hyperlinks.
To find out who links to your site, use
Google's link: tool.
3. Why is my ranking different in Google than
in Yahoo!?
Although Google powers Yahoo's search, our
two sites are not identical in how we handle user queries. Thus, you may
not get exactly the same results when you search using Google.com and
Yahoo!. This is not an error on the part of either engine but merely
reflects differences in the frequency with which the sites are updated and
the number of pages in the index each uses to generate results.
In both cases we try to provide the best
possible search experience for users, which means we do not sell results
or force placement of one site above another. The basic search algorithm
used is exactly the same.
4. I'm changing my URL. How can I maintain my
rank?
Regrettably, we cannot manually change your
listed address at the same time you move to your new site.
That said, there are steps you can take to
make sure your transition is a smooth one. Google listings are based in
part on our ability to find you from links on other sites. To preserve
your rank, you will want to inform others who link to you of your change
of address. One way to find out who is linking to you is to try a link
search. Enter "link:[your full URL]" into the Google search box. You may
not find every page that links to you with this method, but it should help
you begin redirecting the links leading to your site. (Please note: we do
not serve link queries for all of the sites in our index, so this may not
produce any results for your site.)
Finally, if your site goes unlisted for a
time, this does not mean you were dropped from our index. Sometimes, in
these transitions, we will fail to find a site at its new address. Just be
sure that others are linking to you and we should pick you up on our next
web crawl.
Google runs on a unique combination of
advanced hardware and software. The speed you experience can be attributed
in part to the efficiency of our search algorithm and partly to the
thousands of low cost PC's we've networked together to create a superfast
search engine.
The heart of our software is
PageRank™, a system for ranking web pages developed by our founders
Larry Page and
Sergey Brin at Stanford University. And while we have dozens of
engineers working to improve every aspect of Google on a daily basis,
PageRank continues to provide the basis for all of our web search tools.
PageRank Explained
PageRank relies on the uniquely
democratic nature of the web by using its vast link structure as an
indicator of an individual page's value. In essence, Google interprets a
link from page A to page B as a vote, by page A, for page B. But, Google
looks at more than the sheer volume of votes, or links a page receives; it
also analyzes the page that casts the vote. Votes cast by pages that are
themselves "important" weigh more heavily and help to make other pages
"important."
Important, high-quality sites receive a
higher PageRank, which Google remembers each time it conducts a search. Of
course, important pages mean nothing to you if they don't match your query.
So, Google combines PageRank with sophisticated text-matching techniques to
find pages that are both important and relevant to your search. Google goes
far beyond the number of times a term appears on a page and examines all
aspects of the page's content (and the content of the pages linking to it)
to determine if it's a good match for your query.
Integrity
Google's complex, automated methods
make human tampering with our results extremely difficult. And though we do
run relevant ads above and next to our results, Google does not sell
placement within the results themselves (i.e., no one can buy a higher
PageRank). A Google search is an easy, honest and objective way to find
high-quality websites with information relevant to your search.
Determine who link to you
Some words, when followed by a colon,
have special meanings to Google. One such word for Google is the link:
operator. The query link:siteURL
shows you all the pages that point to that URL. For example,
link:www.google.com will show you all the pages that point to Google's home
page. You cannot combine a link: search with a regular keyword search.
