Engines: Different Types
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.
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.
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.
WebCrawler Search Engine
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 http://www.excite.com.
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
search engine (http://www.lycos.com)
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:
offers an advanced search page, at:
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 Shopping.com
and Zip2 Corporation. By August, CMGI, Inc. acquired a majority
of AltaVista stock from Compaq, and Shopping.com and sZip2 became
wholly owned subsidiaries of AltaVista.
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:
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
search engine (http://www.excite.com)
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
For help with
using Excite's query language, click the link for Advanced Search
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.
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
The Hotbot Search Engine
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
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
searches can be narrowed even further, with a level of complexity
not usually found on other search engine sites.
Google Search Page
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.
difference with Ask Jeeves and Ask Jeeves for Kids
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.
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.
list of search engines can be found on Yahoo!, at: http://dir.yahoo.com/Computers_and_Internet/Internet/World_Wide_Web/
or Subject Indices
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.
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.
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.
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.
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.
Gallery feature, at http://gallery.yahoo.com/,
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.
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.
One of the best collections of educational resources on the
Web appears in Yahoo's education listings at http://dir.yahoo.com/Education/
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.
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