Django
Django is a free and open source web application framework written in Python, released under a BSD software license. It is put together as a collection of modules that can be pieced together for rapid development of dynamic websites. It was created out of the code used by Adrian Holovaty, Simon Willison and others working at the Lawrence Journal-World and News, a newspaper in Lawrence, Kansas. The project is named after the Belgian jazz guitarist Django Reinhardt.
It comes built with modules that enable rapid development of sites backed by databases (using an object-relational mapping library) and caching infrastructure, supports URL rewriting (using regular expressions), simple templating and aids in the creation of RSS and Atom feeds. As it came to prominence broadly at the same time as Ruby on Rails, many consider it a competitor or equivalent for those using Python.
Django is offered along with the simple "webapp" framework as one way to build an application for Google App Engine.