A regular expression, often abbreviated as regex or regexp, is a powerful tool used for pattern matching within text. It consists of a sequence of characters that define a search pattern, which can be used to extract or manipulate text data. Regular expressions are widely implemented in various programming languages, including Python, Java, JavaScript, C, and C++ ³⁵.

Regular expressions utilize a combination of normal characters and metacharacters, which have special meanings. For example, the metacharacter “.” matches any single character, while “^” denotes the start of a string, and “$” signifies the end of a string. These patterns can be combined to create complex search criteria, allowing for flexible text processing ²⁴.

In practice, regular expressions can be used for tasks such as validating input formats, searching for specific patterns, and replacing text. They are essential in fields like data science, web development, and text processing due to their efficiency and versatility ¹³.