Welcome to Org Babel reference card. It contains the reference documentation that describes how to perform code execution within Org mode documents using Org Babel 8.
In a nutshell, Org Babel is like Sweave (for reproducible research) but it takes a large number of possible languages (C, Java, Python, Ruby, R, …) and Org mode can produce HTML as well as PDF.
#
#
#
#
#
#
#
#
#
#
See http://org-babel.readthedocs.org/ for full documentation.