Using Search Engines

SEARCH ENGINES

Tutorial Main Page

Subject Directories

Search
Engines

Preparing Your Search

Meta-Search Engines

Specialty Databases

Practice

Other Search Tutorials

Researching Companies Tutorial

Back
to Main Page

Contact Us

Search engines are very different from subject directories. While humans organize and catalog subject directories, search engines rely on computer programs called spiders or robots to crawl the Web and log the words on each page. With a search engine, keywords related to a topic are typed into a search "box." The search engine scans its database and returns a file with links to websites containing the word or words specified. Because these databases are very large, search engines often return thousands of results. Without search strategies or techniques, finding what you need can be like finding a needle in a haystack.

To use search engines effectively, it is essential to apply techniques that narrow results and push the most relevant pages to the top of the results list. Below are a number of strategies for boosting search engine performance. When a "practice" link appears, click on the link to practice the technique with AltaVista's search engine.

IDENTIFY KEYWORDS

When conducting a search, break down the topic into key concepts. For example, to find information on what the FCC has said about the wireless communications industry, the keywords might be:

FCC wireless communication

BOOLEAN AND

Connecting search terms with AND tells the search engine to retrieve web pages containing ALL the keywords.

FCC and wireless and communication

The search engine will not return pages with just the word FCC. Neither will it return pages with the word FCC and the word wireless. The search engine will only return pages where the words FCC, wireless, and communication all appear somewhere on the page. Thus, AND helps to narrow your search results as it limits results to pages where all the keywords appear.

Practice AND

BOOLEAN OR

Linking search terms with OR tells the search engine to retrieve web pages containing ANY and ALL keywords.

(FCC or wireless or communication)

When OR is used, the search engine returns pages with a single keyword, several keywords, and all keywords. Thus, OR expands your search results. Use OR when you have common synonyms for a keyword. Surround OR statements with parentheses for best results. To narrow results as much as possible, combine OR statements with AND statements.

For example, the following search statement locates information on purchasing a used car:

(car or automobile or vehicle) and (buy or purchase) and used

Practice OR & AND

BOOLEAN AND NOT

AND NOT tells the search engine to retrieve web pages containing one keyword but not the other.

dolphins and not Miami

The above example instructs the search engine to return web pages about dolphins but not web pages about the "Miami Dolphins" football team. Use AND NOT when you have a keyword that has multiple meanings. The need for AND NOT often becomes apparent after you perform an initial search. If your search results contain irrelevant results (e.g., Saturn the car rather than Saturn the planet), consider using AND NOT to filter out the undesired websites.

Practice AND NOT

IMPLIED BOOLEAN: PLUS & MINUS

In many search engines, the plus and minus symbols can be used as alternatives to full Boolean AND and AND NOT. The plus sign (+) is the equivalent of AND, and the minus sign (-) is the equivalent of AND NOT. There is no space between the plus or minus sign and the keyword.

NOTE: Infoseek and AltaVista's Simple Search require the use of plus and minus rather than AND, OR, and AND NOT. For Infoseek and AltaVista, the absence of any symbol is the equivalent of OR.

+welding +process

+Saturn -car

couch sofa

IMPORTANT: Use AltaVista's Simple Search for implied Boolean (+/-) searches, and use AltaVista's Advanced Search for full Boolean (AND, OR, AND NOT) searches.

Practice Implied Boolean (+/-)

PHRASE SEARCHING

Surrounding a group of words with double quotes tells the search engine to only retrieve documents in which those words appear side-by-side. Phrase searching is a powerful search technique for significantly narrowing your search results, and it should be used as often as possible.

"John F. Kennedy"

"Walt Disney World"

"global warming"

For best results, combine phrase searching with implied Boolean (+/-) or full Boolean (AND, OR, and AND NOT) logic.

+"heart disease" +cause

"heart disease" and cause

The above example tells the search engine to retrieve pages where the words heart disease appear side-by-side and the word cause appears somewhere else on the page.

NOTE ON IMPLIED BOOLEAN LOGIC (+/-): When a phrase search is combined with additional keywords using implied Boolean logic (+/-), you must put a plus or minus sign before the phrase as well as other the keywords. If the search involves a phrase with no additional keywords (e.g., "Walt Disney World"), the plus sign before the quotes is optional.

Practice Phrase Searching (Implied)

Practice Phrase Searching (Full Boolean)

PLURAL FORMS, CAPITAL LETTERS, AND ALTERNATE SPELLINGS

Most search engines interpret lower case letters as either upper or lower case. Thus, if you want both upper and lower case occurrences returned, type your keywords in all lower case letters. However, if you want to limit your results to initial capital letters (e.g., "George Washington") or all upper case letters, type your keywords that way.

Like capitalization, most search engines interpret singular keywords as singular or plural. If you want plural forms only, make your keywords plural.

A few search engines support truncation or wildcard features that allow variations in spelling or word forms. The asterisk (*) symbol tells the search engine to return alternate spellings for a word at the point that the asterisk appears. For example, capital* returns web pages with capital, capitals, capitalize, and capitalization.

Practice Truncation (Implied)

Practice Truncation (Full Boolean)

TITLE SEARCH

Field searching is one of the most effective techniques for narrowing results and getting the most relevant websites listed at the top of the results page. A web page is composed of a number of fields, such as title, domain, host, URL, and link. Searching effectiveness increases as you combine field searches with phrase searches and Boolean logic. For example, if you wanted to find information about George Washington and his wife Martha, you could try the following search:

+title:"George Washington" +President +Martha

title:"George Washington" and President and Martha

The above TITLE SEARCH example instructs the search engine to return web pages where the phrase George Washington appears in the title and the words President and Martha appear somewhere on the page. Like plus and minus, there is no space between the colon (:) and the keyword.

Practice Title Searching (Implied)

Practice Title Searching (Full Boolean)

DOMAIN SEARCH

In addition to the title search, other helpful field searching strategies include the domain search, the host search, the link search, and the URL search. The DOMAIN SEARCH allows you to limit results to certain domains such as websites from the United Kingdom (.uk), educational institutions (.edu), or government sites (.gov).

+domain:uk +title:"Queen Elizabeth"

domain:uk and title:"Queen Elizabeth"

+domain:edu +"lung cancer" +smok*

domain:edu and "lung cancer" and smok*

The current U.S. domains are the following:

                                    .com   =   a commercial business
                                    .edu    =   an educational institution
                                    .gov    =   a governmental institution
                                    .org     =   a non-profit organization
                                    .mil     =   a military site
                                    .net     =   a network site

Most websites originating outside the U.S. have a country domain indicating the country of origin. For a list of all country domains, visit this site.

Practice Domain Searching (Implied)

Practice Domain Searching (Full Boolean)

HOST SEARCH

The HOST SEARCH comes in handy when you need to find something located at a large site that does not have an internal search engine. With this search technique, you can search all the pages at a website (contained in the engine's database) for keywords or phrases of interest.

NOTE: Because the major search engines do not always log an entire website, use an internal search engine, if the website has one, for best results.

+host:www.disney.com +"special offer"

host:www.disney.com and "special offer"

Practice Host Searching (Implied)

Practice Host Searching (Full Boolean)

URL SEARCH

The URL SEARCH limits search results to web pages where the keyword appears in the URL or website address. A URL search can narrow very broad results to web pages devoted to the keyword topic.

+url:halloween +title:stories

url:halloween and title:stories

Practice URL Searching (Implied)

Practice URL Searching (Full Boolean)

LINK SEARCH

Use the LINK SEARCH when you want to know what websites are linked to a particular site of interest. For example, if you have a home page and you are wondering if anyone has put a link to your page on their website, use the Link search. Researchers use link searches for conducting backward citations.

link:www.pepsi.com

link:www.ipl.org/ref/

Practice Link Searching (Implied)

Practice Link Searching (Full Boolean)

Next Topic