Below are several keyword searching features common to most databases.

Nesting
Nesting enables you to make complex searches. Use parentheses to indicate which terms should be searched together.

(food OR diet OR nutrition) AND cancer
(stress OR anxiety) and (tests OR exams)

Adjacency
In some databases ADJACENCY is assumed when no operator is used. The words must be found together and in that order.  This is also known as automatic phrase searching.  For example, in the Truman Library Catalog and some databases such as EBSCOhost, the following keyword search:
                 holy roman empire  retrieves only  "holy roman empire"

In other databases, adjacency is not assumed and when no operator is specified either AND or OR is the default.  For example:
     
In FirstSearch databases: holy roman empire is searched as holy AND roman AND empire

Truncation
Truncation searches for various forms of a word. A truncation symbol is added to the first few letters of a word to retrieve all of the words that begin with those letters.

          industr* retrieves records with any of these words:
          industry, industries, industrial

The truncation symbol varies in each database.  The most common symbol is the asterisk * used in the Truman Library Catalog  MOBIUS catalog, EBSCOhost databases, and FirstSearch databases. Check the database help screens when in doubt.