Tutorial: Keyword Searching

Combining Terms

Combining Keywords Using Boolean Operators

Usually one keyword isn't specific enough for your topic.

  • There are a few terms that have special meaning to search engines, based on boolean logic.
    • (Remember you learned this in elementary school and thought you'd never use it again?)
  • These terms are boolean operators, and they are used as commands, between search terms.
  • When you use one of these operators the system knows that this term has special meaning and applies it.  
  • Boolean operators are used to combine terms.

The boolean operators you need to understand to start out are AND and OR.


In Omni, boolean operators AND, OR, NOT must be in upper case (caps) to be seen as operators rather than search terms. In most other databases, they are not case-sensitive, so it's not necessary to use caps.

Combining Keywords Using "AND"

Focus your search by adding more search terms and joining them with the word "and". 

  • When you use "and" between terms, you specify that both/all terms must be in every item found.


  • fish and pollution and legislation and ontario
  • atwood and handmaids  
  • videorecording and teachers and racism

Using "and" narrows your search. You find fewer items, but they're more specific because they all contain all the key concepts.

Combining Keywords Using "OR"

Broaden your search by adding more search terms and joining them with the word "or".

  • When you use "or" between search terms, you specify that items must contain one term or the other, but they don't need both.


  • labour or labor  
  • car or automobile or auto
  • indian or native or aboriginal or first nation

Using "or" broadens your search. You find more items, because they only need to contain some of the key concepts.  


Be careful of using both AND and OR in the same search request. 

  • Where possible, use an "Advanced Search" option and place all the OR terms in one box, then use AND between the boxes.

To perform a search all in one line, put brackets ( ) around the OR terms.

  • Example: crayfish and (river or stream)

Searching for a Phrase

When you type two words together, a search engine might assume and AND or OR between them:

  • great lakes = great and lakes 
  • great lakes = great or lakes.

If you want to keep them as a phrase, quotes are a good idea: "great lakes".

  • Then it will look for those words together, and not find items with "great" in one place and "lakes" in another (such as My Great Adventures in the Kawartha Lakes).

Other search engines may have different rules, and you need to check under "Help" to see how to keep a phrase together.

Not all search engines act exactly the same. Although they are all based on boolean logic and understand boolean operators (AND and OR), they might make certain assumptions.

  • A search engine might assume AND or OR between search terms.
  • Or it might make up its own rules. Sometimes + or another symbol is used as an operator.
  • Find out what's happening by looking for a "Help" button and reading the rules for the database you're using.

Better yet, look for an "Advanced Search" option, which helps you organize your search terms by laying it all out for you.

Here's Google's advanced search screen:


screen capture of Google's Advanced Search



See the Omni tutorial for an explanation of Omni's advanced search.