Search Engines

A search engine is a program that searches documents for specified keywords and returns a list of the documents where the keywords were found. Search engines work by sending out a Web crawler, called a "spider," that travels through Web pages by following links and creates an index of all the Web pages it visits. Digital copies of the pages are stored in a database. The search engine then allows users to look for information in this database using a simple or advanced search query.

Search engines make it very simple to find Web pages. The search engine provides an area into which you can type your query. A query is a request for information from a database. In the case of a Web search engine, your query will consist of words that you want to find on Web pages. The search engine will look for these words in all the Web pages in its database.

Google is one example of a search engine. Here is the Google search page with a query on puppies entered into the text field:

Once you have entered your query, you then click on the "Google Search" button, or hit the "Enter" key on the keyboard. Google will then produce a results page that links to the Web pages that include any mention of the word "puppies" from its database.

Here is the Google results page for puppies:

If you look closely at the results, you'll see a wide variety of Web pages about puppies. When using a search engine, you will need to be prepared to spend some time reviewing the results. Not every link that the search engine returns will be relevant to your needs. Later in this lesson, you will explore some advanced techniques to better ensure that the results the search engine gives you are more targeted to your specific needs.

In addition to Google, there are many other search engines you may find useful. Some other search engines are:

• Altavista
• Hotbot
• AlltheWeb

There are also metasearch engines that query other search engines and then combines the results that are received from all; it's as if you're using a number of search engines at once. Some metasearch engines are:

• Metacrawler
• Dogpile

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T R Y   I T   O U T ! Try a search of your own at Google. (Note: This link will open a new browser window. Once you are ready to come back to the lesson, simply close the new browser window.)

P R A C T I C E Use any search engine to find five (5) Web sites that contain biographical information about President Abraham Lincoln.