Searching the World Wide Web
Introduction
• Directories, Search Engines, and Metasearch
Engines
• Search Fundamentals
• Search Strategies
• How Does a Search Engine Work?
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
1
Searching the World Wide Web
Directories, Search Engines,
and Metasearch Engines
• Directories
• Popular Directories
• Search Engines
• Popular Search Engines
• Metasearch Engines
• Popular Metasearch Engines
• White Pages
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
2
Searching the World Wide Web
Directories
Directories, Search Engines,
and Metasearch Engines
• Hierarchical representation of hyperlinks
• Top level of general topics
• Sublevels of more specialized subtopics
• Easy to use
• Not necessary to know exactly what looking for
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
3
Searching the World Wide Web
Directories
• General directory
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•
•
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Web directory
Web guide
Subject directory
Yahoo! --- www.yahoo.com
• Specialized
• Subject guides
• Gateway pages
• Financial aid resource center --- www.theoldschool.org
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
4
Searching the World Wide Web
Popular Directories
Directories, Search Engines,
and Metasearch Engines
• AOL NetFind
• CNET Search.com
• Excite
• Infoseek
• Looksmart
• Lycos
• Yahoo!
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
5
Searching the World Wide Web
Search Engines
Directories, Search Engines,
and Metasearch Engines
• Computer program:
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•
•
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Accepts form containing query
Searches database
Returns URL
Permits query revision
• Specific
• Query syntax
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
6
Searching the World Wide Web
Search Engines
• General search engine
• Google --- www.google.com
• Specialty search engine
• Vertical search engine
• Topic search engine
• MySimon --- www.mysimon.com
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
7
Searching the World Wide Web
Popular Search Engines
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•
•
•
•
•
•
•
Directories, Search Engines,
and Metasearch Engines
AOL NetFind
AltaVista
Excite
HotBot
InfoSeek
Lycos
WebCrawler
Google
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
8
Searching the World Wide Web
Metasearch Engines
Directories, Search Engines,
and Metasearch Engines
• All-in-one search engine
• Call other search engines
• Use single query
• More matches
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
9
Searching the World Wide Web
Popular
Metasearch Engines
Directories, Search Engines,
and Metasearch Engines
• Metasearch
• Metacrawler
• MetaFind
• SavvySearch
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
10
Searching the World Wide Web
White Pages
Directories, Search Engines,
and Metasearch Engines
• Information about individuals
• Bigfoot
• Four11
• WhoWhere
• Yellow pages
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
11
Searching the World Wide Web
Search Fundamentals
• Introduction
• Search Terminology
• Pattern Matching Queries
• Boolean Queries
• Search Domain
• Search Subjects
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
12
Searching the World Wide Web
Introduction
Search Fundamentals
• Information bar
• Search form area
• Directory area
• Links
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
13
Searching the World Wide Web
Search Terminology
Search Fundamentals
• Search tool
• Query
• Query syntax
• Query semantics
• Hit
• Match
• Relevancy score
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
14
Searching the World Wide Web
Pattern Matching Queries
Search Fundamentals
• Enter keyword(s)
• Search engine returns URLs
Boolean Queries
• George Boole
• AND, OR, and NOT
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
15
Searching the World Wide Web
Search Fundamentals
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
16
Searching the World Wide Web
Search Domain
Search Fundamentals
• Current web
• Newsgroups
• Specialized databases
• Internet
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
17
Searching the World Wide Web
Search Subjects
Search Fundamentals
• A way to view the search queries of anonymous
users in real time
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How busy
“Spy” on other users
“See” modifications
Various interests
Personal interests
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
18
Searching the World Wide Web
Search Strategies
Search Fundamentals
• Introduction
• Too Few Hits: Search Generalization
• Too Many Hits: Search Specialization
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
19
Searching the World Wide Web
Introduction
Search Strategies
• Determine which search engine to use:
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•
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•
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User-friendly interface
Documentation
Conveniently accessible
Database size
Relevancy scores
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
20
Searching the World Wide Web
Too Few Hits: Search
Generalization
Search Strategies
• Eliminate keywords
• Remove AND or NOT
• Enlarge search domain
• General keywords
• Directory or metasearch engine
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
21
Searching the World Wide Web
Too Many Hits: Search
Specialization
Search Strategies
• Add keywords
• Add AND or NOT
• Capitalize proper nouns
• Use first 20 URLs
• Directory
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
22
Searching the World Wide Web
How Does a Search Engine Work?
• Search Engine Components
• User Interface
• Searcher
• Evaluator
• Gatherer
• Indexer
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
23
Searching the World Wide Web
Search Engine
Components
How Does a Search Engine Work?
• User interface
• Searcher
• Evaluator
• Gatherer
• Indexer
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
24
Searching the World Wide Web
User Interface
How Does a Search Engine Work?
• Submit queries
• Display results
• Relevancy scores
• Matched page summaries
Searcher
• Program
• Searches database for matches
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
25
Searching the World Wide Web
Evaluator
How Does a Search Engine Work?
• Locates URLs
• Result set
• Factors affecting relevancy score:
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Times query words appear in page
Query words in title
Query words in CONTENT attribute
Number of query words appearing in document
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
26
Searching the World Wide Web
Gatherer
How Does a Search Engine Work?
• Traverses Web
• Breadth-first search
• In levels “across” pages
• Depth-first search
• Chain of hyperlinks “down”
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
27
Searching the World Wide Web
How Does a Search Engine Work?
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
28
Searching the World Wide Web
How Does a Search Engine Work?
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
29
Searching the World Wide Web
Gatherer
How Does a Search Engine Work?
• Miscellaneous facts:
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•
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Heavy load on Web servers
Restricted depth of searches
Trouble with framed documents
Dependent on collection of documents
Full text indexing
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
30
Searching the World Wide Web
Indexer
How Does a Search Engine Work?
• Organizes (indexes) gathered data
• URL
• Document title
• Descriptive keywords
From Greenlaw/Hepp, In-line/On-line: Fundamentals of the Internet and the World Wide Web
31