I got from Macromedia DEVNET great resources about REGEX
The origins of regular expressions date back to the 1950s when mathematicians began exploring theoretical computer science. This field of research included topics such as automata theory and formal language theory. Stephen Cole Kleene, one of the fathers of theoretical computer science, is credited with inventing regular expressions. Ken Thompson, a major contributor to the development of the UNIX operating system, incorporated regular expressions into the UNIX text editor known as Ed.
Depending on the tool or language, the implementation of regular expressions may vary. Due to the varying levels of support, I recommend that you always find documentation on what is and is not supported by the tool or language that you’re using. There are a variety of reasons why the growth in popularity of regular expressions has taken place. For web developers and programmers, the quantity of code in the world has grown exponentially. As such, it’s become increasingly difficult to navigate the volume of text that is out there. In addition, although regular expressions ancestry stems from mathematics followed by programming, regular expressions can be used by content developers as well to update large amounts of text easily.