AND narrows a search because the more terms you join with AND the fewer results you will receive.
Truncation is used to indicate that any form of a root word is to be retrieved.
When using a World Wide Web database or search engine, check its help screens to determine if truncation is allowed and how it is to be used. NOT may not be a valid operator in all databases. With the Alta Vista search engine, for example, you must use AND NOT . Consult the help screens to determine what options are possible. Nesting must be used in most databases when a search statement involves OR and another operator.