I am by no means an expert in the field. Regular expression use to be a thing that only UNIX users knew about. Then along came Perl, which has been described as the next step from sed and awk since it combines the functionality of these two programs, plus allows the use of C and Fortran libraries. However, when Microsoft started creating scripting languages for the Windows platform, only JScript contained regular expression, leaving VBScript alone in the dark. That has changed, though, with version 5 of the VBScript Engine.
Regular expression is, technically, a defined grammar for use in complex pattern searching.
Very, very neat stuff. Character matching is the easiest, so let's start there. You can also search for strings which contain characters which fall in a set of characters. Let's say that you wanted to find strings like 1Guys, 2Guys, 3Guys, or 4Guys. You can also use the dash as a range value.