Please take care to read Joost's answer carefully, spotting the needed differences. Perl has two quoting approaches: single quotes (that basically don't interpolate) and double quotes (that do interpolate). So:

my $variable = 42;
print 'this is $variable'; # prints   this is $variable
print "this is $variable"; # prints   this is 42
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More on this in perlop, under "Quote and Quote-like Operators".