Perl has a rich set of built-in routines and access to most of the interesting functions in the C library. The manual pages for Perl go into exhaustive detail about all of these routines so I will simply discuss a few of the more commonly used ones. Most of these descriptions are paraphrased from the man pages (and a few are shamelessly copied word for word).The default argument for most of these routines is $_. Note that parentheses around function parameters are usually optional.