Through a database lookup or search function, the user can enter a set of keywords. In that case, you need to parse the input field; that is, break it into a list of individual words or terms.
The process of parsing is fairly straightforward. The first step is to define the whitespace characters that can separate the terms in your input field. Whitespace is usually defined as blank, or space, characters, and tabs. It may also include carriage returns and linefeeds, as well as certain other nondisplaying characters.