Following up on what myocom said, everything following the ? in a web URL is called a query string. It takes the form:

name_1=value_1&name_2=value_2&name_3=value_3
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where both have been encoded in a particular way. For instance if your variable names were city, date and max_temp you might see:

city=New+York&date=20010912&max_temp=79
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A complete CGI script that uses this might be:

#! /usr/bin/perl -w
use strict;
use CGI qw(:standard);

my $city = param('city');
my $date = param('date');
my $max_temp = param('max_temp');

print header( -type=>'text/plain' ),
  "The hottest it got in $city on $date was $max_temp F.";
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