In computing, a regular expression is a specific pattern that provides concise and flexible means to “match” (specify and recognize) strings of text, such as particular characters, words, or patterns of characters. Common abbreviations for “regular expression” include regex and regexp.
Basic Concepts A regular expression, often called a pattern, is an expression that specifies a set of strings. To specify such sets of strings, rules are often more concise than lists of a set’s members.