Best Regular Expression Dev Tools
Just a quick post to point out some fantastic web applications to help you craft regular expressions in your text processing adventures. These tools make it vastly easier to develop a solid understanding of regular expressions compared to when I learned them by studying the classic O'Reilly book Mastering Regular Expressions
First Place: RegEx 101
RegEx 101 is the overall best tool. The explanation block clearly explains how each part of your regular expression is interpretted. The syntax highlighting is great, and the UI doesn't have any confusing parts about whether you need the surrounding slashes and so forth.
RegExplained has a great railroad diagram visualization of your regular expression.
regexr is also handy although not as polished as RegEx 101.
Get out there and be glad you may be able to get away without staring at the pages of this book for hours on end.