Searching the World Wide Web

CMP 101 Introduction 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 you looking for?

Type of search Examples Broad range of topics in a specific category A lot of information about a specific topic.

Specific facts Subject Directory Meta-search engine Individual Search Engine

 

Astronomy Football

   

Aurora Borealis (Northern Lights) Indianapolis Colts Aurora Borealis particle speed Peyton Manning’s passing statistics 9

Basic Search Techniques

Be specific Put 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….

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