- The true power of regular expressions — it also includes a nice explanation of what regular means in this context
- softwareengineering: Is it a must for every programmer to learn regular expressions?
- softwareengineering: When you should NOT use Regular Expressions?
- codinghorror: Now You Have Two Problems — demystifies the often (mis)quoted meme
- wikipedia: Regular expression — this article includes discussion on regular expressions as a formal language as well as details about various implementations
- swtch — stuff about regular expression implementation engines
Note that some of these resources are not specific to Python. So you'll have to adapt them to Python's syntax.
- docs.python: Regular Expression HOWTO
- Python 3 Module of the Week: re — covers till Python version 3.7.9
- stackoverflow: python regex
- PythonVerbalExpressions — construct regular expressions with natural language terms
- CommonRegex — collection of common regular expressions
- Awesome Regex — curated collection of libraries, tools, frameworks and software
- Generate strings that match a given regular expression
- stackoverflow: regex FAQ
- stackoverflow: regex tag is a good source of exercise questions
- rexegg — tutorials, tricks and more
- regular-expressions — tutorials and tools
- regexcrossword — tutorials and puzzles, only supports JavaScript flavor
- regex101 — visual aid and online testing tool for regular expressions, select flavor as Python before use
- debuggex — railroad diagrams for regular expressions, select flavor as Python before use