Learning Regex
The items in this first section are visual and interactive demonstrations of concepts in Regex. The resources in the second section, pulled from an up-to-date version of Awesome Regex, are part of a more complete summary of Regex learning resources. Also see this web book's Online Learning Overview and Massive Open Online Courses pages, which emcompass Regex (but also other topics') resources as well.
Select Interactives and Visualizations
The Bastards Book of Regular Expressions