What are the most common operators?
The most common operators are + (plus), - (minus) and " "(quotes). They are the operators that all the major search engines understand. They are also the operators that are most frequently used.
What does the + operator do?
The + operator tells the search engine to retrieve only documents that include the term it is used with. For example: +curriculum +english, will only return documents that have both of those terms. The + operator must be used before each term that must be included. For example curriculum +english +science +art will return documents that have all the words curriculum, english, science, art. Google and other search engines automatically add the AND operator between search terms. This makes the + operator unnecessary. Most search engines treat + and AND the same way.
However, with search engines (such as AltaVista) that automatically insert OR between search terms, the + operator overrides OR and will only return documents that include the term. For example, on AltaVista, curriculum english, will return documents with the term english OR curriculum. However +curriculum +english will return only documents with both terms.
Try it! What happens to a query when you string together synonyms? Using the same search engine you tested for default operator settings, let's search for those rhinos again. This time gradually add more names for rhino to your query and watch what it does to the resulting citations. (Use professional vocabulary and other synonyms.)
For example: I am searching for information on coffee. I start with the query terms of +coffee +java. As I begin to skim the results I find more and more synonyms and related terms until I have the query +coffee +java +"coffee cherry" +peaberry +robusta +arabica +liberica +kaffa. What do you get for rhino?
What does the - operator do?
The - (minus sign or hyphen character) operator tells search engines to exclude documents that contain the term it is used with. Example: high school -curriculum would exclude any document with the word curriculum in it.
Try it! Go back to your search engine again. Try the minus operator on a few of your new rhino terms. What happens to the results?
For example: When I use +coffee -java -capucino -mocha as my query, I get results from exclusively British and US companies none from the equitorial countries who grow the coffee beans.
What does the " " operator do?
The " " (also called quotes) operator turns two or more individual terms into a single phrase that is searched for together and in order. The quotes operator can also be used to tell some search engines to include words that they may normally exclude, such as a, and, the or other common terms as, for example, "to be or not to be."
Try it! Which phrase will return the most accurate data on the rhino? How often does it appear?