Principles of Regular Expressions for an SEO Author Tomasz Rudzki Read bio Regular expressions are powerful and convenient tools. Thanks to them, you no longer need to search for a particular text string by hand. Paul Shapiro called regular expressions “find-and-replace on steroids.” By using regular expressions, you can define a pattern (it can be, for example, any website URL or any e-mail address) to be found in a text. They can be a real time-saver when working with unordered and messy data. By reading the tutorial, you will learn: How to search for URLs, status codes. How to extract anchors from links. How to filter server logs to Googlebot. How to use a Notepad++ text editor to easily replace text fragments based on regular expressions.