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 utilized in various programming languages, including Python, Java, JavaScript, C, and C++ ³⁵.

The structure of a regular expression includes both 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 ³⁴. Regular expressions can also include character classes, quantifiers, and operators to refine the search criteria further.

Regular expressions are particularly useful for tasks such as validating input, searching for specific patterns, and performing text replacements. They can be complex, but with practice, they become an invaluable asset for text processing and data manipulation ¹².