Perl is a popular programming language that is extensively used in areas such as bioinformatics and web programming. It's become popular with biologists because it is so well suited to several bioinformatics tasks. This appendix is geared to those who are attempting the language for the first time.
Perl is also an application and is available (at no cost) to run on all operating systems found in the average biology lab (Unix and Linux, Macintosh, Windows, VMS, and more). The Perl application on your computer takes a Perl language program (such as one of the programs in this book), translates it into instructions the computer can understand, and runs (or executes) it.
The word Perl, then, refers both to the language in which you write programs and to the application on your computer that runs those programs. You can always tell from context which of these two meanings is being used.
Every computer language such as Perl needs to have a translator application (an interpreter or compiler) that can turn programs into instructions the computer can actually run. The Perl application is often referred to as the Perl interpreter, and it includes a Perl compiler as well. You will also see Perl programs referred to as Perl scripts or Perl code.