Final answer:
A regular expression is a sequence of characters that defines a search pattern used in computer science to match and manipulate text based on certain patterns. They are powerful tools that can save time and effort when working with text data.
Step-by-step explanation:
A regular expression, also known as regex or regexp, is a sequence of characters that defines a search pattern. It is used in computer science, especially in programming languages and text processing tools, to match and manipulate strings of text based on certain patterns. Regular expressions are used in a wide range of applications, from simple password validation to complex data extraction and search operations.
For example, let's say you have a text file containing names and email addresses. With a regular expression, you can search for all the email addresses in the file by defining a pattern that matches the structure of an email address.
Regular expressions are powerful tools that can save a lot of time and effort when working with text data. However, they can also be quite complex, and learning how to use them effectively requires practice and understanding of their syntax and rules.