Search Concepts for All Electronic Databases
The following concepts are common to most computer databases of bibliographic information, including the library catalog.
- The full citation containing information about a title is called a "record".
- Each element of information in the record (author, title, subject) is called a "field".
- A controlled vocabulary often exists for precise subject access - look for an index or thesaurus.
- COMMAND KEYS (function keys, keypad [KP] keys, or buttons) appear on each screen.
- One of the commands is a "HELP" key or button which should explain each function.
- Words can often be truncated using an "*", "?".
- When starting a search, use the most specific or "narrow" term or concept first.
- Find out the features which are used to narrow or limit the scope of your search.
- Understand Boolean logic.
Boolean Logic for Combining Terms
The phrase to remember is: "OR" gets more while "AND" gets less
The computer is looking for individual records. Whatever you search for must be contained in each record. Therefore, using the example below,
"AND" between terms narrows the search by requiring that BOTH terms appear in each record. 
Asking for Holistic medicine (A) AND headaches (B) will get only those titles which have BOTH terms assigned to each record. See shaded area above.
OR" between synonymous terms in a search broadens the scope.
If the search is for marital psychotherapy(A) OR marriage counseling(B), the results will be all those titles which are about marital psychotherapy PLUS all those titles which are about marriage counseling. See shaded area above.
"NOT" between terms narrows the search by eliminating the records that contain one of the terms. 
If you want to search for violence, but not domestic violence, you would phrase the search as violence(A) NOT domestic(B). Some computers may require you to use the phrase "AND NOT" between terms.