Ever need to verify that an email follows the proper format? Or the phone number a person enters is a correct US phone number? If so you must have been working with Regular Expressions. People tend to shy away from RexEx stuff but this free online site is there to help you perfect a craft that will surely reap you benefits once you master the skill.
RegExr is an online tool for learning, editing, and testing regular expressions
Here’s the link: http://gskinner.com/RegExr/