Perl, also Practical Extraction and Report Language (a backronym, see below), is an interpreted procedural programming language designed by Larry Wall. Perl borrows features from C, shell scripting (sh), awk, sed, and (to a lesser extent) many other programming languages.

Perl has been used since the early days of the web to write CGI scripts, and is now a component of the popular LAMP (Linux/Apache/MySQL/Perl) platform for web development. Perl has been called "the glue that holds the web together". Large systems written in Perl include Slashdot, and early implementations of Wikipedia and PHP.

Perl finds many applications as a glue language, tying together systems and interfaces that were not specifically designed to interoperate. Many systems administrators use Perl as an all-purpose tool; short Perl programs can be entered and run on a single command line.

Perl is widely used in finance and bioinformatics, where it is valued for rapid application development, ability to handle large data sets, and the availability of many standard and 3rd-party modules.

Python is an interpreted, interactive programming language created by Guido van Rossum in 1990. Python is fully dynamically typed and uses automatic memory management; it is thus similar to Tcl, Perl, Scheme, and Ruby. Python is developed as an open source project, managed by the non-profit Python Software Foundation. Python 2.4.1 was released on March 30, 2005.

Like Lisp, and unlike Perl, the Python interpreter also supports an interactive mode in which expressions can be entered from the terminal and results seen immediately. This is a boon for those learning the language and experienced developers alike: snippets of code can be tested in interactive mode before integrating them into a program proper.

Python also includes a unit testing framework for creating exhaustive test suites. While static typing aficionados see this as a replacement for a static type-checking system, Python programmers largely do not share this view.

Standard Python doesn't support continuations (and never will, according to Guido van Rossum), but there is a variant known as Stackless Python that does.