The Python Standard Library > 6. Text Processing Services > re
Regular expressions HOWTO:
For … science underlying regular expressions (deterministic and non-deterministic finite automata), you can refer to almost any textbook on writing compilers.
Metacharacters are not active inside classes: … '$' is usually a metacharacter, but inside a character class it’s stripped of its special nature.
Perhaps the most important metacharacter is the backslash, \.
Some of the special sequences beginning with '\' represent predefined sets of characters
* doesn’t match the literal character *; instead, it specifies that the previous character can be matched zero or more times, instead of exactly once.
Pay careful attention to the difference between * and +;
match() versus search()
Python Regular Expressions
Christopher Potts emoticons
Python: Regular expressions
University of Cambridge