http://www.perlmonks.org?node_id=89547

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Since some may not have access to Jeffery Friedl's "Mastering Regular Expressions" or can't afford to buy it (i.e., casualties of the dot com bust), could someone EXPLAIN, in plain English ("talk to me like I'm a five year old"), WHY one would use the pattern:
delimiter normal* (?:special normal*)* delimiter
when dealing with multiple level quantifiers in regular expressions. There are enough references to and examples of this technique on this site but no write-ups explaining how it effects the PERL regex engine. Thank you in advance.