1 searching the world wide web cmp 101 introduction to information systems l02. internet search
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Searching the World Wide WebCMP 101Introduction to Information Systems
L02. Internet Search
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What is the World Wide Web?
Billions of Documents– Accessible via the Internet – Viewed by a web browser.
Web documents contain hyperlinks – Allow readers to jump from one web
document to another– Gateways to audio and video broadcasts,
animations, and more.
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What is a Search Engine?
A collection of software – Locates words on web pages– Ranks and indexes the words– Creates a database that you can
search.
When using a search engine, you search the database that has been created (not the Web).
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How Does a Search Engine Work?
Robots, Spiders, Crawlers – Oh My!– visits web pages – collects words and hyperlinks– gives words to the search engine for
ranking and indexing– differing strategies for crawling yield
different results
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How Does a Search Engine Work?
Ranking and Indexing – Meta-information
• the number of times a word appears on a page• the word’s location on a page• other much more sophisticated information.
– differing strategies yield different results
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Subject Directories
Categorical listing of topics with links to individual web sites. Created with the help of human editors Editors rate and rank the sites Good for narrowing down a topic or browsing a large list of topics.
Examples include: Yahoo! Directory (dir.yahoo.com), and Gigablast (gigablast.com).
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Individual Search Engines
Create and maintain a database of indexed and ranked words for searching. Good to use if looking for specific information about a topic.
Examples Include: Google (google.com), Yahoo! Search (yahoo.com), and Ask (ask.com).
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Metasearchers
Searches multiple individual search engines Presents results in one convenient list. Good to use to get a feel for how much information is available on a topic.
Examples include Dogpile (dogpile.com), Mamma (mamma.com), and Clusty (clusty.com).
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Search strategy kickoff
Determine your needs:
What are youlooking for?
Type of search Examples
Broad range of topics in a specific category
Subject Directory
Astronomy Football
A lot of information about a specific topic.
Meta-search engine
Aurora Borealis (Northern Lights)
Indianapolis Colts
Specific factsIndividual
Search Engine
Aurora Borealis particle speed
Peyton Manning’s passing statistics
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Basic Search Techniques
Be specificPut words in the order you would normally expect them to appear.Avoid using common words.Consider synonyms.Use search focus options: (i.e. images, videos, or blogs).
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Advanced Search Techniques
Boolean logic (AND, OR, NOT): – Boolean AND
• Include all words. • Narrows your search.
– Boolean OR• Include any of the words• Broadens your search. • Useful for synonyms.
– Boolean NOT or AND NOT• Excludes words• Narrows your search
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Advanced Search Techniques
Implied Boolean operators (+, -)– Used in place of the Boolean AND and
Boolean NOT.
Phrase searching (“ “)– Place quotes around a phrase.– Returns documents where the words
appear as a phrase (side by side).
Wildcards (*): – Used for plurals, alternative endings, or
alternative spellings,
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Advanced Search Techniques
Advanced search form– With all the words: Same as using the
AND or plus (+) operator.– With at least one of the words:
Same as using the OR operator.– With the exact phrase: Same as
using quotes.– Without the words: Same as using
the NOT or minus (-) operator.
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Analyzing results
Scan through the first five to ten pages of results. Consider synonyms.Use the NOT or minus (-) operator.Broaden your search.Narrow your search.
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Odds and Ends
Search engines ignore some pages.– dynamic (created on demand) such as
a request for account information, – require registration or a login (like the
Wor-Wic research databases).
database not always up-to-date.
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Odds and Ends
Search within a site.
Search for individual words or phrases on a page – Edit > Find on this page… on the
menu– Search List arrow,
Find on this Page….