Unit 1—Computer Basics

Lesson 3The Internet and Research

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Objectives

List some reasons for searching the Internet.

Describe different search approaches.Define a search engine.Explain how search engines work. Identify some of the more popular search

engines.

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Objectives (cont.)

List some of the specialty search engines. Describe some search tips and tricks. Describe the subject directory search

approach. Describe the invisible Web.

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Why Search the Internet?

Reasons that people search the Internet Research for school assignments Looking for medical and scientific

information Travel information and accommodations Shopping for goods and services

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Internet Search Tools

There are two basic types of Internet search tools: Search engines

Perform searches based on keywords Subject directories

Search by specialized topics What is the difference between them?

Search engines are automated. Directories are assembled by people.

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What Is a Search Engine?

Search engines are programs that allow you to search for information.

There are hundreds of search engines on the Internet.

Search engines allow keyword searching. Some support concept-based searching. Some support stemming.

The list of results returned from your search are called hits.

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Search Engine Components

Search engines usually have three main components. The search engine program that does the search

of its database A spider or crawler that looks for the information

in the database The index that is built from information returned

by the spider

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Keyword Searches

Keyword searches look for specific words within a Web page.

Many search engines use meta tags to build their search index. Meta tags are HTML tags in a Web page that

do not display, but can be used to define page content.

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Keyword Searches (cont.)

Search engines also use significant words to build their index. Significant words may be words mentioned near the

beginning of a page or repeated frequently throughout the page.

Some search engines claim to index all words in a Web page.

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Keyword Search Steps

To search using keywords: Connect to the Internet and go to a search engine

site. Enter your keywords in the search box.

Many search engines allow you to enter a phrase or sentence.

The search engine examines its internal database index looking for your words.

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Keyword Search Steps (cont.)

To search using keywords (cont.): The search engine returns a list of hyperlinks (hits)

to Web sites containing your words. Click a hyperlink to go to that site.

If you get no hits on your search, revise your keywords and try again.

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Major Search Engines

Although there are hundreds, these are some of the more well known search engines: Yahoo at yahoo.com Microsoft at msn.com America Online at aol.com Ask Jeeves at ask.com Netscape at netscape.com

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Specialty Search Engines

These also are called category-oriented search engines.

They are commonly used for Locating people Finding shareware and freeware Shopping Sports-related information Career planning

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A Specialty Search Web Site

This figure shows the Beaucoup Web site page. Note the various categories of information available.

Clicking a sub-category will bring up a new page of categories until you find the exact topic you are searching for.

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Tools and Techniques for Searching

Some commonly used techniques Phrase searching Search engine math Boolean searching Wildcard searching Title searching

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Phrase Searching

This is used to search for words that must appear next to each other.

Phrases must be enclosed in double quotation marks. “Books on the Civil War”

Only sites with the exact phrase will be returned as hits.

You should capitalize proper nouns.

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Search Engine Math

Use math symbols to enter formulas or to filter out unwanted listings. A plus sign (+) before a word means it must

appear. A minus sign (-) before a word means it should

not appear.

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Search Engine Math (cont.)

Examples of search engine math To search for sites that contain both cookies

and recipes, enter+cookies+recipes

To exclude sites that have coconut cookie recipes, enter

+cookies+recipes-coconut

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Boolean Searching

Boolean logic is similar to search engine math, but is more powerful.

Boolean logic consists of three operators: AND: Search for sites that include Word A AND

Word B. NOT: Search for sites the include Word A but NOT

Word B. OR: Search for sites that include Word A OR

Word B.

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Wildcard Searching

Wildcard searching allows you to search for words for which you may not know the spelling or to search for plurals or variations of a word.

The wildcard character (*) lets you search for any word that has the characters before or after the wildcard character.

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Wildcard Searching (cont.)

Wildcard search example To search for the element potassium without

knowing how it is spelled, enterPO* or po*ium

Not all search engines support wildcard searches.

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Related Searching

Some search engines have a related search feature. The search engine will return hits based on your search

criteria and may also display a list of other sites that have information related to your search criteria.

This can greatly improve the odds of finding the information that you want.

Note: Some sites call this feature similar pages or more pages like this.

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Subject Directory Searching

Subject experts personally examine Web sites and add the URL to a search engine if it meets standards.

Subject directories are organized by subject categories.

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Subject Directory Searching (cont.)

Subject categories Each category has a collection of links to Internet

resources. The resources are arranged by subject and

displayed in menus. You start at the top of a category and drill down from a

generic start to a specific topic.

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A Subject Directory Site

This figure shows the Yahoo Subject Web site.

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Advantages of Subject Directory Searches

They usually provide a more guided approach than keyword searches.

They are easy to use. You are not searching the entire Web. The linked sites have been handpicked and

evaluated. Most links include a description. They produce better quality hits on searches for

common items.

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Popular Subject Search Sites

About: about.comThe Librarians Index: www.lii.comYahoo: www.yahoo.comGalaxy: www.galaxy.com

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Advanced Search Forms

This figure shows the advanced search form for the AltaVista Web site. It is designed to assist you in performing advanced searches by providing

text box options.

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The Invisible Web

Also known as the “deep Web” Indexes searchable databases

Resources www.completeplanet.com www.profusion.com

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Summary

Search engines and directories are two basic tools that you can use to find information on the Web.

People assemble directories; search engines are automated.

A search engine is a software program. Most search engines support keyword searches.

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Summary (cont.)

Concept-based searching occurs when the search engine returns hits that relate to keywords.

Stemming relates to the search engine’s capability to find variations of a word.

Meta tags are special tags embedded in a Web page; many search engines use the tags to create their indexes.

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Summary (cont.)

Keywords describe the information you are trying to locate.

Search engines contain a database of organized information.

Some search engines use natural language. A search engine has three main parts: the search

engine software, a spider that searches for keywords, and an index.

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Summary (cont.)

Stop words, such as www, but, and or, are not indexed by many search engines.

A search engine uses an algorithm to index Web sites.

Specialized search engines focus on a particular topic.

Multimedia search engines focus on video, animation, graphics, and music.

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Summary (cont.)

Subject directories are organized by subject categories.

Subject experts check the Web sites that are part of a subject directory’s database.

Use double quotation marks around a set of words for phrase searching.

Use the plus and minus signs for inclusion and exclusion of words within a search.

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Summary (cont.)

Boolean searching uses the three logical operators OR, AND, and NOT.

The * symbol is used for wildcard searching.

No single organization indexes the entire Internet.