# Regular Expressions

Regular Expressions are how you match text and patterns of text in a programming language, and once you learn it, it’s useful in many languages.

- [Regular Expression Cheat Sheet](http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/)
- [RegExr is an online tool to learn, build, & test Regular Expressions](http://regexr.com/)
- [<span class="caps">CROSSWORDS</span> <span class="caps">HELP</span> <span class="caps">YOU</span> <span class="caps">LEARN</span> <span class="caps">REGULAR</span> <span class="caps">EXPRESSIONS</span>](http://hackaday.com/2016/01/31/crosswords-help-you-learn-regular-expressions/) – *Jan. 31, 2016*