A regular expression is used to match or search for specific text

patterns within a larger body of text. It consists of a sequence of characters that form a search pattern, which can be used to find or replace text in a document or string of text. Regular expressions are commonly used in programming languages, text editors, and other tools for manipulating text. They provide a powerful and flexible way to perform complex search and replace operations, and can be used to search for specific patterns of characters, such as email addresses, phone numbers, or URLs.