Searching information on computers (Boolean operators)

Boolean operators

The most common Boolean operators are AND, OR and NOT (always in capitals). They can be used to get more accurate search results.

AND

The words 'black' and 'shoes' will return results that contain the words 'black' and/or 'shoes'. You may get results that contain only one of the two words, eg ‘purple shoes for sale’ or ‘black T-shirts for sale’.

In general, search engines treat the query ‘black shoes’ as ‘black AND shoes’ - which means results must contain both words, eg ‘black shiny shoes for sale’.

Sometimes you have to add AND to get results that contain both words. This won’t guarantee that the words will appear next to each other, only that both words will be present in results, eg ‘black T-shirts and purple shoes for sale’.

OR

Use OR to request an alternative, for example ‘black OR white shoes’. Most search engines would interpret this as ‘black OR white AND shoes’.

NOT

NOT tells a search engine what to ignore. The query ‘shoes NOT brown’ will return results that contain the word shoes but NOT the word brown. Some search engines use a minus sign in front of the word instead of NOT, eg -brown.

Quotation marks

Although not strictly a Boolean operator, quotation marks can be used to get more accurate results. For example, use “black shoes” to get results where the words ‘black’ and ‘shoes’ appear together, eg ‘black shoes for sale’. By doing this, the result ‘black T-shirts and purple shoes for sale’ will not be returned.