Regular expressions are used to perform matches and substitutions on strings
Regular expressions can include meta-characters (characters with a special meaning, which describe sets of other characters) and quantifiers
Character classes can be used to specify any single instance of a set of characters
Alternation may be used to specify any of a set of sub-expressions
The matching operator is m/PATTERN/ and acts on $_ by default
The substitution operator is s/PATTERN/REPLACEMENT/ and acts on $_ by default
Matches and substitutions can be performed on strings other than $_ by using the =~ binding operator
Functions such as split() and grep() use regular expression patterns as one of their arguments