INTERNET RESEARCH

What is a search engine?

• A huge database of web page information, assembled by computers, that allows end-users to locate web sites containing the information they are looking for

How do Search Engines Work?

• Use “spiders” or “robots” to crawl through the web from site to site

• Create an index of the words on various sites and build a database of these words

• When you perform a search, the search engine looks for your request in it’s database

• FYI – When you use a search engine, you are not searching the entire world wide web – just the portions that have been “spidered” and “indexed” by that particular search engine

• Therefore try different search engines if you are not happy with your results

Types of Search Engines

• Individual– compile their own databases on web content

• Meta– don’t compile databases; use the databases of

many other search engines at the same time• Subject Directories

– Created and maintained by human editors, not computers; usually a table of contents-style listing of subjects is included for you to click on; some search only the sites directory, some search both the directory first and then the entire web

Examples of Individual Search Engines

• VISIT this website• published January 2015 on the top 15

search engines

http://www.ebizmba.com/articles/search-engines

Examples of Meta Search Engines

• Visit this website for the top 10 Meta Search Engines published in 2014:

http://www.listofsearchengines.org/meta-search-engines

Examples of Subject Directories

• www.looksmart.com• www.lycos.com• www.completeplanet.com• www.excite.com• www.yahoo.com• www.netscape.com• www.beaucoup.com

Boolean Logic

• Refers to relationships between terms• Devised by Irish mathematician, George

Boole• One way of improving search results• Examples: OR, AND, NOT• Must be typed in uppercase when used

Example of using OR

• Will find websites containing…– Only the word weightlifting, – Only the word bodybuilding, or– Both of the words weightlifting and bodybuilding

• Like saying…– “Find me sites with information about weightlifting

or bodybuilding. I don’t care which.”

Weightlifting OR bodybuilding

•The OR expression is especially useful where there is a synonym for the word you are looking for.

•Example:–attention deficit disorder OR ADD–influenza OR flu

Example of using AND

• Will only find websites containing…– Both of the words, internet and security– Will not find sites containing only internet– Will not find sites containing only security

• Like saying…– “I want information about internet security. I don’t

want information about the internet in general, or about any other kind of security.”

internet AND security

Example of using NOT

• Will find websites containing…– The word gambling but will then eliminate the

ones that also contain the word lottery

• Like saying…– “I want to find information about gambling but I do

not want information about lotteries. I only want to explore other forms of gambling.”

gambling NOT lottery

The NOT expression should be used with caution. You could potentially eliminate some useful sites. Using the previous example, you might eliminate a site that contains exactly the gambling information that you are looking for, but it also happens to contain information on the lottery.

Combining Boolean Expressions

• Boolean operators can be combined to further improve your search results

• Examples:

oceans OR lakes AND pollution

Nurses AND malpractice NOT doctorsChildren NOT infants AND psychology

Combining Boolean Expressions• Care must be taken when doing this or

you won’t get the results you desire• What are the differences here?

oceans OR lakes AND pollution

oceans AND pollution OR lakes

oceans OR pollution AND lakes

Other Search Tips and Techniques

Put Most Important Words First

• Search engines focus on your entry from left to right

• E.g.– Focus is on dog

• E.g. – Focus is on family

dog breed family pet choosing

family pet choosing dog breed

Use Quotation Marks

• Will find websites containing…– The exact phrase located in the quotation

marks in the exact order; does not look for individual words in the quotation marks

“Canada Customs and Revenue Agency”

Use a Plus Sign

• Forces search engine to include all of the words with the plus sign

• Similar to the AND expression• Note: no spaces between the sign and

the word; one space between terms

+pizza +recipes

Use a Minus Sign

• Forces search engine to exclude all of the words with the minus sign

• Similar to the NOT expression• Note: no spaces between the sign and

the word; one space between terms

+chihuahua -training

Use all Lowercase

• Typing in lowercase finds matches in both lower and uppercase

• In some search engines, typing in uppercase results in only matches that are in uppercase as well– E.g.

– may not find sites containing the word president (with a lowercase p)

President

Use a Wildcard

– Useful when there are two spellings of a word– Most common are the * and ? (if supported)– E.g. colour therapy vs. color therapy

– Also used for variations of a word– E.g. psychology, psychological

colo*r therapy

psycholog*

Omit ‘Stop Words’

– Words that search engines generally do not search for

– E.g. a, about, an, and, are, as, at, be, by, from, how, i, in, is, it, of, on, or, that, the, this, to, we, what, when, where, which, with, etc

– Note: when using Boolean expressions (AND, OR, NOT), they must be typed in uppercase in order to not get ignored

• Remember all search engines are different. Some support all, of most of, the information in this presentation; some do not support certain techniques. Details can be found at each particular website.