Regular expressions are a concise, specific, and flexible way to match strings of text commonly used in programming languages and regularly allowed in configurations to extend flexibility to all sorts of processes. Not surprisingly, people began noticing these patterns even before wide-spread programming. Analyzing strings of text is very much like math. Regular Sets were first introduced in the 1950′s. Regular expressions can also be called RegEx which can be quite complex and often times confusing. Let’s take a look at how regular expressions can be used.
Check out some examples here: http://www.regular-expressions.info/examples.html
Some great examples of using RegEx can be shown using Linux and Grep:
Here is a brief presentation of how RegEx can be used in SQL: