Regular expressions are that makes Perl an ideal language for "Practical extraction and reporting" as the name implies.To construct the regular expression, which is essentially a sequence of characters describing the pattern you would like to match. In MS-DOS we use "*.txt" to get all text files, we say this as a pattern, likewise perl uses a set of regular expressions that can be used to specify the patterns, so you can make your search more specific.

After creating a regular expression perl uses binding operators like (=~ or !~) to bind the data to be searched for. Let us see a example.

Perl is used in number of ways:

• Search for a string that matches a specified pattern
• Optionally replacing the pattern found with some other strings
• Counting the number of occurrences of a pattern in a string
• Split a formatted string (e.g. a date like 02/06/2001) into day, month and year
• Validation of fields received from HTML forms by verifying it to a particular format