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978-0-470-09712-0
Let’s say you have searched on dog breeds. The results are innumerable (actually just over 11 million). This
is far too many pages to search manually. At this point you have two options: Go back and form a more spe-
cific query, or search through the 11 million results to narrow the number. At the bottom of the results page
you will see a link, Search within results. Clicking this link will cause a new Search within results search
box to appear. Enter a new search term. Continuing this example, try typing “fox terrier”. Even though
this example returns 780,000 results, they are more specific to the dog breed fox terrier. Unfortunately you
cannot continue searching through your results a second time. If there are still too many results and not
specific enough you will have to go back and form a better query. Knowing how Google does is job can help
you form better queries.
is far too many pages to search manually. At this point you have two options: Go back and form a more spe-
cific query, or search through the 11 million results to narrow the number. At the bottom of the results page
you will see a link, Search within results. Clicking this link will cause a new Search within results search
box to appear. Enter a new search term. Continuing this example, try typing “fox terrier”. Even though
this example returns 780,000 results, they are more specific to the dog breed fox terrier. Unfortunately you
cannot continue searching through your results a second time. If there are still too many results and not
specific enough you will have to go back and form a better query. Knowing how Google does is job can help
you form better queries.
How Google Searches the Web
To get the best out of Google it helps to know a little bit about how Google goes about searching the Web.
This will help you create better queries and understand the results you are seeing and why they are ordered
the way they are. Google ranks the results of a search by using “traditional” factors such as the URL (Web
page address such as
This will help you create better queries and understand the results you are seeing and why they are ordered
the way they are. Google ranks the results of a search by using “traditional” factors such as the URL (Web
page address such as
www.google.com
), meta tags (invisible pieces of information about a Web page
added by a Web page author), keywords (search terms), and its own patented technology called PageRank.
Google follows four steps to complete the search:
n
Finds all the pages that match the keywords on the page.
n
Ranks the pages using “traditional” factors (URL, meta tags, and keyword frequency).
n
Calculates the relevancy of the link text. How related are the keywords to what appears in the link?
n
Google displays the results using PageRank to determine the result order.
Google employs search bots (Web crawlers), which are special programs that search through Web pages,
evaluating the pages based on certain criteria and creating an index that allows for rapid search results.
evaluating the pages based on certain criteria and creating an index that allows for rapid search results.
Traditional factors
There is certain information within a Web page that Web crawlers look at to analyze where a page should
fall within the results of a search. The term for this is relevancy. Pages in a search engine most often appear
in the results based on the most relevant pages first. There are several factors in determining the degree of
relevancy a page might have. Some of these are obvious, such as the keywords appearing within the text of
the Web page. Other, less obvious, factors are involved in determining the relevancy of the page. These
include meta tags, descriptive tags, and link text.
fall within the results of a search. The term for this is relevancy. Pages in a search engine most often appear
in the results based on the most relevant pages first. There are several factors in determining the degree of
relevancy a page might have. Some of these are obvious, such as the keywords appearing within the text of
the Web page. Other, less obvious, factors are involved in determining the relevancy of the page. These
include meta tags, descriptive tags, and link text.
Meta tags
Meta tags refer to information that is placed within the header of a Web page that is not visible to the per-
son viewing the page. The information in these tags, which is stored in name/value pairs, is passed to search
bots or Web crawlers like the ones Google uses. The information stored in these tags often includes key-
words and descriptions of the page that the Web page author would like to associate with the page.
son viewing the page. The information in these tags, which is stored in name/value pairs, is passed to search
bots or Web crawlers like the ones Google uses. The information stored in these tags often includes key-
words and descriptions of the page that the Web page author would like to associate with the page.
Even though Google does not give these tags much weight, it still looks for keywords in them. There are many
types of meta tags but the two most commonly used for assisting in PageRank are the
types of meta tags but the two most commonly used for assisting in PageRank are the
<DESCRIPTION>
tag
and the
<KEYWORD>
tag. The
<DESCRIPTION>
tag includes a text string describing the contents of the page.
This is the description used by Google and other search engines to describe the page to Web searchers. The
<KEYWORD>
tag contains a comma-delimited list of keywords the Web page author feels are important in find-
ing the Web page. This includes terms that may not be found within the actual text of the page. For example,
an e-commerce site might include keywords such as hefty man in the
an e-commerce site might include keywords such as hefty man in the
<KEYWORD>
tag but not include this
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Searching the Web
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