Search Engines Explained

From its inception the Internet has posed to its users the problem of how to get the information they need from a large network of interconnected computers. If you know which particular Web site has your information and you know its URL (see the definitions section of "What Technologies?" for a definition of "URL), it is simply a matter of typing it into the address bar at the top of your Web browser. But much, if not most, of the time you will be looking for specific information without knowing which particular Web site has that information. In such cases even a huge directory listing every Web site that currently exists would be of little use. So how do you find the Web site you really want on a World Wide Web that contains millions upon millions of sites?

You use a search engine.

Select a question below to learn more about search engines.

1. What is a search engine and how does one work?
   
2. What are some popular search engines?
   
3. Are there any search engines designed for kids?
   
4. Do search engines index the entire Internet?
   
5. What are Boolean operators?
   

What are Boolean operators?

Boolean operators get their name from George Boole, the logician who invented them in the nineteenth century. In the context of the World Wide Web, they can help you and your child do more precise searches, which can in turn save both of you a lot of time. The following are the most commonly used Boolean operators.

• AND. Use AND between search terms if you want only Web pages that contain all of the terms. For example: Election AND Florida.



• OR. Use OR between search terms if want the search engine to return Web sites that contain one search term or the other. For example: Lawyer OR Attorney.



• NOT. Use this operator to exclude Web sites that have certain words. For example: Telephones NOT mobile.



• "" (Quotation Marks). Putting terms between quotation marks makes the search engine look for those words as a phrase on the Internet. For example: "George W. Bush"

Much of the time you will find that Boolean operators are not necessary, but it's good to know them if a search isn't giving you the results that you wanted.

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