Search Engines: Different Types

Search Engines are based on computer programs that are sent out to scan the contents of servers on the World Wide Web. Information is indexed by relevance.

In this section, we'll take a look at some of the most popular general-purpose search engines. However, keep in mind that all of these search engines may look very different the next time you see them; the appearance and interface of a search engine can change considerably over the course of even a few months. Luckily, the general ideas behind effective use of a search engine-structuring your queries, choosing what kind of results you want, and identifying strengths and weaknesses-should always remain true, no matter what kind of search engine you use.

note.gif (1073 bytes) Because most search engines are supported by the sale of advertising, a trend at sites that host search engines is to provide a variety of "value-added" information as well so that you'll frequently use their site. So, don't be surprised to find that search engine sites also offer services like index-style directories of reviewed web sites, random links for spontaneous surfing, news services, chat rooms, and more. For example, WebCrawler (see below) has some interesting special features such as Search Voyeur, a java applet that continuously displays actual searches that people are doing on WebCrawler.

Search Engine Features

Many search engines allow you to search for pictures, sounds (specifically, MP3), for people (through people finders), videos, and maps & driving directions. A "Family Filter" or Filter is also available on many search engines so that objectionable material may be filtered out of your search results. This useful feature allows teachers or parents who do not want young web users gaining access to the many adult-oriented sites on the Internet to filter out objectionable material.


.  WT_fig75.jpg (12188 bytes)
.The WebCrawler Search Engine

The WebCrawler search engine, originally developed by Brian Pinkerton at the University of Washington, was the first full-text search engine available on the web. WebCrawler at one time was owned by America Online but has now been acquired by Excite, Inc., (which has it's own search engine at And as successful technology companies continue to be acquired by larger successful technology companies, AtHome, a high-speed Internet service company, bought Excite for more than $7 billion in stock.



Lycos Search Page

The Lycos search engine ( is named after a predatory wolf spider of the family Lycosidae. Lycos lets you construct somewhat more sophisticated queries than WebCrawler, allowing you to choose the desired amount of relevance as well as the format of the output.

For more information about using Lycos, check out:

Lycos also offers an advanced search page, at:


WT_fig7_11.jpg (12666 bytes)
Altavista Search

AltaVista ( is a search engine originally developed and maintained by Digital Equipment Corporation. After DEC was acquired by Compaq Computer Corporation early this year, Alta Vista became a wholly owned subsidiary of Compaq Computer which also purchased and Zip2 Corporation. By August, CMGI, Inc. acquired a majority of AltaVista stock from Compaq, and and sZip2 became wholly owned subsidiaries of AltaVista.

In addition to searching for web sites, AltaVista also allows users to search for graphic images, audio and video clips. A "Family Filter" is available so that objectionable material may be filtered out. This useful feature allows teachers or parents who do not want young web users gaining access to the many adult-oriented sites on the Internet to filter out objectionable material. More information about the family filter option is available at:

Like most major search engines, AltaVista allows you to perform either a simple or a complex search; our example shows an advanced search. For complete information on structuring queries for Alta Vista, follow the links for "Help" and for "Advanced Search."



Excite Search Form 

The Excite search engine ( is unusual because it uses "fuzzy" logic instead of Boolean logic. Documents in the Excite database are indexed not only by the keywords they contain, but also by synonyms for the keyword, so a search can be broadened to include items that are relevant but don't contain the exact words you entered. For example, a search for the words "software piracy" at a traditional search engine would only return documents containing those words. A search at Excite would also return documents containing the words "intellectual property," since it's a related concept.

For help with using Excite's query language, click the link for Advanced Search Tips.

As mentioned earlier, these search engine sites want to become "portals" to the Internet. They want users to come back to their site and continue to use their services, instead of a competing search engine site. They in turn can then sell more and higher-priced advertising. As with traditional media advertising, the more "viewers" they have, the more money they can charge their advertisers.

To make their sites even more appealing, Excite, like most of the other major search engine sites, allows you to customize the page. If you provide your zip code and birth date for example, the search page can include such individualized features as regional news items, sports scores, weather, movie and television listings for your area, and your personal horoscope. They hope that this will be an incentive for you to return to this search engine site whenever you are looking for information. Some search engine sites include a button that you can click to make their site the default homepage for your web browser, so that when you launch the browser, it will automatically go to their portal page.

Excite's results are grouped by categories that include directories, web sites, news articles and online discussions. The results include a confidence rating of how much the Excite engine thinks each result matches your request.



WT_7_17.jpg (12686 bytes)
The Hotbot Search Engine

Hotbot (, sponsored by Wired Magazine's online HotWired publication, is based on the lnktomi search technology created at the University of California at Berkeley as part of a project to create scalable computer systems, that is, systems that can be expanded as the need for additional resources grows. HotBot has now been acquired by Lycos.

HotBot's interface allow users to create some of the most complicated searches you can perform on the web, including limiting the search to a range of dates, document types, and even whether or not the page includes javascript. By clicking on the Advanced Search button, searches can be narrowed even further, with a level of complexity not usually found on other search engine sites.  



Google Search Page

Google ( is a fairly recent addition to the search engine field. Headquartered in Mountain View, California, Google was founded in 1998 by two Stanford Ph.D. students, Larry Page and Sergey Brin. What makes Google different from most other search engines is that it caches the web sites that are indexed in its database--that is, it keeps a stored copy of the page in its database. This means that when you try to connect to a site that Google returned, and that site is unavailable for whatever reason, you can still view a previously cached version of that page.



Other Search Engines

Ask Jeeves

The difference with Ask Jeeves and Ask Jeeves for Kids (, is that these search engines were among the first to allow users to write their questions in plain language. For example, a question like "What is the tallest building in the world?" produces a link to a page entitled "Whose building is tallest? Kuala Lumpur has the edge on Chicago" which describes how the Petronas Towers in Kuala Lumpur, Malaysia, is 33 feet taller, if you count the spires, than the 1,450-foot Sears Tower in Chicago.

Ask Jeeves for Kids promotes itself as a "safe way for kids to find answers to their questions online. Ask Jeeves for Kids is primarily an educational Web site that kids can use for homework help and research for school projects" and only provides access to "G-rated" web sites.

A comprehensive list of search engines can be found on Yahoo!, at:


Unified Search Pages or Meta-Search Engines

Meta-search Engines search the databases of other search engines' and collate the results. Usually a predetermined number of results will be returned from each of the search engines' databases that are used. A Meta-search Engine does not not maintain its own index or database.

These are single pages where you can actually submit queries to several different individual search engines.
 A popular unified search location is available as part of at

Unified Search Form at's main search engine is just like many of the other standard search engines we've looked at. But's search feature uses many other search engines to conduct your search, all from the same web page. Just enter your query, and click Search. 

More Meta-Search Engines:


Sends queries to a customizible list of up to 25 search engines including: Yahoo!, Lycos' A2Z, Excite Guide,, HotBot, PlanetSearch,, Thunderstone, What U Seek, Magellan, Lycos, WebCrawler, InfoSeek, Excite & AltaVista. Also, Newswires, FTP and Usenet.


The Mother of all Search Engines


Sends search queries to several search engines including: Lycos, Infoseek, WebCrawler, Excite, Alta Vista and Yahoo, then normalizes and ranks results. Of special interest: using Power Search, allows user to limit by continents and by U.S. educational, commercial or government sites.

For more information about meta-search engines like the ones listed above, see:
The Meta-Search Engine Web Page from the University of California, Berkeley


Directories or Subject Indices

Directories are put together by humans rather than computer programs. They may be general or subject specific, and they may be searched by a keyword. These are usually sites that attempt to organize large amounts of information or that specialize in organizing information in a specific subject area.

Search engines are great if you have a pretty good idea of what you're looking for, as they let you locate specific information quickly. But if you're looking for general information on a topic, a search engine might not always be the right tool. Since entering a good query requires that you be as specific as possible, you might not see sites that contain information on related topics or that are simply indexed under a synonym for your search terms. If you're looking for a broader range of information than a search engine provides, check out one of the subject indices listed below.

A subject index works just like an index in the offline world. Several top-level categories are displayed, such as Commerce, Education, and Entertainment. Clicking a top-level category displays subcategories, which you can navigate through until you reach a page of links to sites that fall into the same classification.


Yahoo! is one of the most popular subject indices available today. Originally developed in April, 1994 by David Filo and Jerry Yang, doctoral students in Electrical Engineering at Stanford University, Yahoo! quickly grew to be one of the most popular sites on the web.

The San Jose Mercury News says "Yahoo is closest in spirit to the work of Linnaeus, the 18th century botanist whose classification system organized the natural world." True, Yahoo!'s categories are comprehensive enough to include almost anything you can think of. Many categories are cross-referenced so you can reach the same information from different paths. Yahoo! also provides an advanced search mechanism to search the titles that are cataloged at the site, as well as their own "What's New" pages and  links to many of the information resources available on other major search sites.

Yahoo!'s Picture Gallery feature, at, is a searchable index of graphic images available at the sites listed in the Yahoo! directory. You can enter terms that describe the image you're looking for, or you can browse different categories to see all the available images under that heading.

A financial arrangement with software gant SoftBank and a public offering in 1996 gave Yahoo! the capital to create a slew of additional services, including an interactive map (type a street address anywhere in the United States and see it on a map; you can then pan or zoom around it) an index of images, where you can look for pictures instead of text; articles directly from the Reuters news wire; and more.

teacher.gif (565 bytes) One of the best collections of educational resources on the Web appears in Yahoo's education listings at 



Yahooligans! is a site developed by Yahoo! that's strictly for kids. It's a child-safe version of their larger subject index, containing sites of interest to children, parents, and educators alike, with links in categories for the arts, entertainment, science, and more.

Other Subject Directories:
The Human Internet

Education World
Although this site bills itself as a search engine, its contents are small enough that it's most useful as a subject index for all kinds of information related to education, such as developmentally appropriate practices, home schooling, online learning, and a number of other relevant topics.


Formerly known as EINet Galaxy and then Tradewave Galaxy, the Austin-based company sponsoring this index recently changed the corporate name and the name of their web sites and products. Now simply known as the Galaxy, this subject index is not as comprehensive as that of Yahoo, but does offer multiple layers of categories. But it does not contain so many entries that you find yourself clicking through a seemingly never-ending maze before you arrive at a page of useful information.

For more information or a list of subject directories, go to the UC Berkeley Library at

Guides to Specialized Search Engines

The complete list of guides (with descriptions) to thousands of search engines covering hundreds of subjects. Listed in approximate order of size, specificity of subject categories, and some aspects of search engine collection quality.


This site allows you to choose a catagory and a country to find specialized search engines. You also have the option of entering a keyword.



Web Resources

Hypersearching the Web - from the online version of Scientific American

Evaluating Search Engines

Sink or Swim: Internet Search Tools & Techniques

Search Engine Watch

Windweaver's Search Guide - Using the Best Directories and Search Engines

Understanding And Comparing Web Search Tools

Comparison of Search Engine User Interface Capabilities