Download Search engine lecture

Search Engines & Subject
Directories (Portals)
• Once there was a clear distinction between
search engines & subject directories
• Now, most such sites combine the former
strength of both into a single portal site
• www.hotbot.com
• www.lycos.com
The Internet
• E-mail
• Chat
• World Wide Web
How to access the Internet and
Web
• At your local library
• Contract with an ISP (Internet Service
Provider)
Things Needed to go on the
Internet at Home
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An ISP (Internet Service Provider)
A telephone line
A computer
A modem
Software
Qualities of a good ISP
• It should have an access telephone number
that is a local call for you
• Availability of technical assistance
• Size of the company is not an issue
• Choice of access tools or browsers –
Netscape Navigator or Internet Explorer
• Look for higher speeds
Finding what you want on the
Internet
• Finding what you want isn’t quite as easy as
typing a question and getting an answer
• To be an efficient finder, you need to know
what’s on the Web and to find it fast
• Some effort and study are required
URL : Universal resource
Locator
• Quick way to find information on Web
• Don’t use a portal if you have the URL or
are able to guess it
• Type in www.name of organization and
domain name
• Enter a URL exactly as it’s written
• www.google.com
Domain Names
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.com – company
.edu – education
.gov – government
.mil – military
.net – network
.org - organization
Finding a URL for an
organization
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Go directly to a portal
www.google.com
www.excite.com
Sheboygan Press
Supreme Court of the United States
Milwaukee Brewers
Subject Directories
• Web (subject) directories are hierarchical
catalogs of the World Wide Web
• Major topic headings are broken down into
smaller areas that are, in turn, broken down
further
• Web directories work like the old-fashioned
card catalog
• www.yahoo.com
Yahoo : a subject directory
• www.yahoo.com
• When you visit a directory site, you see a
list of major categories along with selected
subcategories
• Clicking any category or subcategory
displays another page with more entries
When to use a subject directory
• Directories are great for finding general
information on popular topics and for narrowing
down your search
• They’re a good way to explore a topic and learn
more about related topics
• Homepages display the major categories, and then
you click your way through the category structure
• Keyword searches can be performed
Search Engines
• A search engine is a machine that executes a
search function on the pages that comprise the
Web
• Many search engines are available
• To operate a search engine you must type a word
or phrase into the search box and start the search
• Results are listed in groups of 10 to a page
• Click an item that appears helpful
When to use a Search Engine
• You don’t have the time to discover where a topic
you want to find might be located within the
hierarchy of a directory’s items
• You can guess that the Web sites you seek may not
be popular enough to be listed in the categories of
a directory
• The desired information is precise and involves a
number of limiting criteria (“Summertime square
dancing events held in Sioux City, Iowa”)
Meta-Search Engines
• They don’t have their own databases;
instead, they search other search engines
simultaneously and group the results on one
page
• www.dogpile.com
Subject-specific search engines
• For specific searches on narrow topics, subjectspecific search engines are often better than
general engines
• Specialized search engines are available for nearly
every imaginable topic
• These specialty databases contain only
information on that given topic
• www.beaucoup.com/
• www.internets.com
Best search engines (portals)
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Google www.google.com
Ask Jeeves www.ask.com/
Dogpile www.dogpile.com
Excite www.excite.com
GoTo www.goto.com/
Hot Bot www.hotbot.com/
LookSmart www.looksmart.com/
Northern Light www.northernlight.com/
Yahoo www.yahoo.com
Power searching : refining your
search
• Capitalize words only when you’re sure that they
would be stored that way – names of people or
places, for example
• Put quotation marks (“”) around words you expect
to see next to each other in the results
• Put a + in front of a word that must appear in your
results
• Expand search results by connecting keywords
with OR
More power searching tips
• Make sure that you put a space before the + or –
and no space between it and the word
• Most search engines do not index punctuation
• Use an * wildcard character to search for variant
spellings. For example, theat* matches theatre
and theater
• If you don’t find a desirable answer, express your
search in different wording
Bookmarking
• Finding Web pages that yield precisely the
information you’re looking for can
sometimes be time consuming, so you don’t
want to repeat the entire process to revisit
favorite Web pages
• Simply bookmark the site so it is always
immediately accessible
Stop Words
• Words that search engines ignore because
they are too common
• Examples : the, to, with, from, for, of, that,
who, and, not & or
• The list can vary in each search engine
Help Screens
• Every search engine has explanations how
their database is most effectively used
• Click that link of any portal and you’ll get
detailed help information
• www.yahoo.com
• www.altavista.com
Evaluating the source
• When you find apparently good results, pause and
evaluate the source
• For example, health sites provided by hospitals or
official organizations are more likely to contain
high-quality material than commercial sites selling
health products
• The domain name may give a clue to reliability
• Look at the link on the homepage that describes
the providers, like “About us,” “Who we are,” and
so forth
Habits of highly effective
searchers
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Develop the Internet habit
Use the best tool for the job
Choose unique keywords
Use various portals
Consider the source
Practice, practice, practice
Know when to look elsewhere
Tutorials
• Home.sprintmail.com/~debflanagan/main.ht
ml
• www.lib.berkeley.edu/TeachingLib/Guides/I
nternet/FindInfo.html
• http://204.17.98.73/midlib/tutor.htm
• http://w3.one.net/~alward/
• www.learnthenet.com/english/index.html
Keeping up-to-date with search
engines
• Search Engine Watch
• www.searchenginewatch.com/
1) click search engine listings
2)click major search engines
3)click The major search engines
4)Scroll down