I don't need to test my programs. I have an error-correcting modem.
Python is an interpreted scripting/programming language which I happen to be quite fond of. It tends to fill roughly the same niche as Perl, and sometimes this gets some people arguing about which is better. Python can easily be used for short scripts, larger programs, CGI, even GUI applications. It's easy to write modules which extend Python, either in Python or as native code.