What is a regular expression?

A regular expression is a powerful tool in computer science, specifically in the context of text processing. It serves as a sequence of characters that defines a search pattern, primarily used for string searching, manipulation, and validation. Regular expressions allow users to specify complex search criteria, such as matching specific character sequences, identifying patterns, and even replacing portions of strings based on defined rules.

For example, a regular expression can be used to validate email addresses by specifying the required format, ensuring users enter valid values. This makes regular expressions an essential component of data validation and text processing tasks, enabling programmers and cybersecurity professionals to work efficiently with large datasets and secure user inputs.

The other options, although relevant concepts in their respective areas, do not accurately define what a regular expression is. Therefore, understanding the role and function of regular expressions is crucial for effective programming and text processing within cybersecurity practices.