Boolean Search Operators for the search engines:

Boolean
Definition
+
Display only mandatory word, eg. +Coventry
-
Excludes the word, eg. +Coventry -University
<
The word that follows has a lower relevance than other words.
>
The word that follows has a higher relevance than other words.
()
Used to group words into subexpressions.
~
The word following contributes negatively to the relevance of the row (which is different to the '-' operator, which specifically excludes the word, or the '<' operator, which still causes the word to contribute positively to the relevance of the row.
*
The wildcard, indicating zero or more characters. It can only appear at the end of a word.
"
Anything enclosed in the double quotes is taken as a whole. eg. "Hello World" will match the entire sentence "Hello World"