Boolean Searching: AND, OR, NOT
AND - narrows your search: politics AND art > retrieves documents that include politics AND art; both terms in a documents for it to be retrieved.
OR - expands your search: politics OR government > retrieves documents that include EITHER politics OR government. Either term can appear in a document for it to be retrieved. Use OR when you are using synonyms in your search terms.
NOT - narrows your search (politics AND art AND california) NOT baja > will leave out documents that include references to Baja California
Truncation: Finds variant word endings
politic* > Retrieves: politics, politician, political
Subject vs. Keyword searching
The subjects that are assigned to items come from a set list of words, concepts, and phrases (controlled vocabulary). Controlled vocabularies have strict rules concerning how terms are applied. And while we sometimes don't always agree with the terms that are used - it's useful to understand the language that is used to describe your subject.
When you select the "subject" field to be searched, you are only search that field. You are NOT searching any other part of the record.
When you perform a keyword search, you are searching the record in its entirety. In other words, the search engine is searching the title field, the author field, contents, subject, etc. This can be a good or bad thing, depending on your results. Too many results: modify by adding keywords, or selecting a specific field to search. Not enough results, change the keywords you are using.