Imagine a complex search term with Boolean connectors, such as 'murder or manslaughter and provocation or insanity'. The sequence in which the operations (and, or) are carried out depends on which of them has priority.

Each search system has its own inbuilt priority rules but you can override these by stating your own, using brackets (parentheses) as you would in an algebraic equation.

Expressions within brackets will always be treated as an entity and evaluated before other expressions.

Look at the diagram below. Think about which of the three search terms shown would find the documents in all the areas coloured blue. Click on the terms for feedback.