Are you having problems finding exactly what you want with just a keyword search? Advanced Search operators provide ways to further refine your search query. One type is the Boolean operator, named after British mathematician George Boole (1815-1864), who made a study of combining logic with mathematics.
Major search services support Boolean operators, but each search service may implement them differently.

Boolean operators are connecting words--words that you can use to specify relationships between the keywords or phrases in your search query. Boolean operators can be used as words or as symbols:

When you select "all of the words" on a search page, it is the equivalent of keyword1 AND keyword2 AND keyword3... and so on. When you select "any of the words" on a search page, it is the equivalent of keyword1 OR keyword2 OR keyword3... and so on.
Although you can use symbols instead of the actual word, use of the actual word is recommended; different search engines may use different symbols to represent Boolean operators, but the actual words will always be the same.

You can compose search queries by grouping keywords and Boolean operators. This allows you to look for references that contain this AND that, but NOT something else.
The next lesson will introduce ways of refining a search that are more restrictive than AND, OR, and NOT, but Boolean operators may still be a good choice for some complex search queries.

Click the Exercise link below to compare search results with different Boolean operators and grouping.
Search Boolean Operators - Exercise