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Logical operators AND, OR, and NOT

The logical operators AND, OR, and NOT can all be used to restrict results returned from a search.


The OR operator returns results that have either one string or the other. The OR operator can be used multiple times in a search string, however, one thing to watch for when using operators other than AND is that each word is considered a search term so the search string

 university degree OR high school diploma 

has five search terms--not two--and does not return results that have either the phrase university degree OR the phrase high school diploma. Nor does it return results that have university AND degree OR high AND school AND diploma because there are different ways to parse that search string which would yield different results. For that reason we require explicit grouping of search terms in complex searches. More on how to use complex searches below.


Sometimes a search will return a lot of items that are related to each other and not of interest to you and you need to be able to winnow out extraneous results. E.g.:

  • wildlife - Returns several thousand results--many of which seem to be about wildlife refuges instead of wildlife.

Insert the operator NOT before the text you want left out of your search and you can cut the number of results significantly.

  • wildlife NOT refuge - Gets the number down significantly and shows you what else you might want to remove.

The NOT operator, like the OR operator, can be used more than once in a search:

  • wildlife NOT refuge NOT "us-doi-gov" - Returns results that match wildlife and do not contain refuge or us-doi-gov. At this point you might have a better idea what keywords are common to the results you want and you can search for them with AND or OR.

NOT, like OR cannot be used in complex searches (combined with AND or OR) without specifying the grouping of the search terms.


Using the operator AND is not necessary because AND is the default operator for searches on The search string

  • colony collapse - returns anything with the words colony and collapse somewhere in the search fields