ACCESSING DATABASES FOR INFORMATION RETRIEVAL

Search Engine Limitations

When you search for information using a search engine, you are only searching through a small subset of the information available electronically via the web. This is because search engines crawl and index HTML documents. Recall that HTML is the standard used to mark-up text so that it will display properly through your browser. Much of the information that is available via the web is not stored in the form of static HTML documents, but rather it is stored in databases, and programming allows the contents of these databases to display HTML documents upon request. An example of this dynamic display is what happens when you search at a search engine. As described in the last section, when you search at a search engine, you are searching the database of sites maintained by the search engine. The search results you get display as an HTML web page, but that exact page did not exist until you submitted your search. It was dynamically generated in response to your search, displayed for you as an HTML web page, and will not exist indefinitely. Similarly, there are many databases full of information that, while accessible over the web, do not exist as static HTML pages. The contents of these databases will not be indexed or searchable using a standard search engine. 

Accessing the Information in Databases Via the Web

To get to this "hidden" information, considered part of the "Invisible Web," you must first search for the database itself, and then search the database for the specific information you need. This strategy means that you must first think broadly about your topic, placing it in a larger category of information. For example, if your topic is "Internet Addiction" you might try to find a database related to mental health, and then search it for articles on your specific topic. If your topic is treating diseased roses, you might try to find a database of gardening articles, and then search it directly for your specific needs. 

Fortunately, some specialized tools exist to assist you in finding databases, the contents of which you can then search directly. www.invisible-web.net is one such tool. 

Practice: go to www.invisible-web.net and click on the link for "Health." Now select a subcategory of your choice. The results should show a list of health-related databases. Try searching in a few of these databases for information on a topic of your choice. 

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