Mastering regex is a life-altering discipline. If you eat meat, you must become a vegetarian, and if you are a vegetarian, you must start eating meat.

Or, you could just "RTFM"... perlretut (for beginners), and perlrequick (for the impatient), and perlre (The Whole Truth).

When you need some diversion from all that, you can also browse the output of perldoc -q regex and perldoc -q regular -- some really choice bits there.