Introduction to Web Searching
Alton Patrick
This introduction is on a very elementary level and assumes no experience
with search engines. If you feel relatively comfortable with the syntax of
searching, you might find a more in-depth look, like
AltaVista's
Help page, more useful.
A List of Popular Search Engines
IntroductionA search engine is a program that keeps records of millions of web pages. There are lots of search engines on the Internet -- AltaVista, Infoseek, Lycos, Excite, Magellan, Webcrawler, and Yahoo are some of the more popular ones. Search engines use programs called "robots" which spend their time reading web pages and noticing which words are on which pages. In addition, search engines let people who write web pages submit a description of their page to be added to the list of pages the search engine knows about.
You'll probably never need to know about robots. You will need to know how to get search engines to tell you which pages might interest you. There are a couple of ways to do this. The first is called a category search and is useful if you want information on a general subject. Yahoo (http://www.yahoo.com) is a good place to do this kind of
search.
Category Searching with YahooOn Yahoo's main page is a list of categories that Yahoo has information about. Each of these links takes you to a page with more related categories. The broadest topics are first, and they get narrower as you go deeper. So, to find pictures taken by the Hubble Space Telescope, you might follow these links:
Searching by KeywordA more common type of search is a keyword search. Keyword searches are faster than hunting through a hierarchical index like Yahoo's, but they often turn up a lot of pages that don't really relate to the subject you were searching for. For example, instead of going through the list of subjects above to find Hubble Space Telescope pictures, you could use this query string in a keyword search:
The words you type are referred to as a "search string" or "query string." Each page a search engine returns in response to your query is a "hit." Sometimes a search can return a lot of hits. Another popular search engine is AltaVista (http://www.altavista.digital.com). Go there now. In the middle of the page is a text box. This is where you type your search string. Type in the following:
AltaVista will return a page with a list of links to pages that contain the word "bat." A line near the top of this page tells you how many hits the search generated: "About 52250 documents match your query." 50,000 web pages is a lot to look through. There are several ways to narrow down the number of hits you get, depending on what type of information you are looking for. Try typing in this search string:
Now try this search string:
Look at the list of links that your search for +bats -baseball generated. Near the top there should be one for "Re: Approved bats for USSSA etc." -- a baseball related topic. Why? You told the search engine to exclude pages related to baseball, right? Not exactly. You told it to exclude pages that use the word "baseball," which is slightly different. While it's usually safe to assume that pages about a subject will all use certain words related to that subject, it's not always the case. In this instance, the word "baseball" does not appear anywhere in the text of the page about USSSA bats. Search engines aren't perfect. They can reduce the amount of work you have to put into finding something, but you still have to carefully sift the information they return. Here's one more way to narrow a search. Try this search string:
SummaryTo review, here are three simple ways to narrow a keyword search:
- Any word with a minus sign in front of it must not be on a page. "" Words with quotation marks around them must all appear within a few words of each other on a page. When all else fails...When trying to come up with a search string, think about what words you would use in writing about the subject you're researching. Especially think of words and phrases that are specific to that subject and make it stand out from others. Unfortunately, you will often get thousands of hits, no matter how much thought you put into your search string. Remember that the first few are statistically the most relevant (they use the specified keywords most often, etc.). You should start with those pages. Don't ignore the links on pages -- even if the page you're looking at isn't useful itself, it might have a link to just the information you need. Still, you might have to click on quite a few pages until you find one that is really helpful. Sometimes there is no substitute for effort.Also, don't limit yourself to just one search engine. No one engine even comes close to indexing every page on the World Wide Web. If you don't have any luck with the first search engine you try, try another one. Be sure to remember, however, that the syntax for searching presented in this tutorial is for AltaVista; other search engines may have their own operators for building search strings.
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