searching the world wide web

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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 DirectoriesCategorical 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 EnginesCreate 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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MetasearchersSearches 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 kickoffDetermine 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 facts Individual Search Engine

Aurora Borealis particle speed

Peyton Manning’s passing statistics

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Basic Search TechniquesBe 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 resultsScan 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 EndsSearch 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 EndsSearch 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….