Regex Concept

In computing, a regex, or regular expression, provides a concise and flexible means for "matching" (specifying and recognizing) strings of text, such as particular characters, words, or patterns of characters. The concept of regular expressions was first popularized by utilities provided by Unix distributions, in particular the editor ed and the filter grep. A regular expression is written in a formal language that can be interpreted by a regular expression processor, which is a program that either serves as a parser generator or examines text and identifies parts that match the provided specification.