Our search engine allows queries to be formed from arbitrary Boolean expressions containing the keywords AND, OR, and NOT, and grouped with parentheses. For example:

electronic e-commerce
finds documents containing 'electronic' or 'commerce'

electronic or commerce
same as above

electronic and commerce
finds documents containing both 'electronic' and 'commerce'

electronic not commerce
finds documents containing 'electronic' but not 'commerce'

web*
finds documents containing words starting with 'web'