Cython is an optimising static compiler for both the Python programming
language and the extended Cython programming language (based on Pyrex).
It makes writing C extensions for Python as easy as Python itself.

Cython gives you the combined power of Python and C to let you

- write Python code that calls back and forth from and to C or C++ code
  natively at any point.
- easily tune readable Python code into plain C performance by adding
  static type declarations, also in Python syntax.
- use combined source code level debugging to find bugs in your Python,
  Cython and C code.
- interact efficiently with large data sets, e.g. using multi-dimensional
  NumPy arrays.
- quickly build your applications within the large, mature and widely
  used CPython ecosystem.
- integrate natively with existing code and data from legacy, low-level
  or high-performance libraries and applications.

The Cython language is a superset of the Python language that additionally
supports calling C functions and declaring C types on variables and class
attributes. This allows the compiler to generate very efficient C code
from Cython code.
The C code is generated once and then compiles with all major C/C++
compilers in CPython 2.6, 2.7 (2.4+ with Cython 0.20.x) as well as 3.3
and all later versions.
We regularly run integration tests against all supported CPython versions
and their latest in-development branches to make sure that the generated
code stays widely compatible and well adapted to each version.
PyPy support is work in progress (on both sides) and is considered mostly
usable since Cython 0.17. The latest PyPy version is always recommended here.

All of this makes Cython the ideal language for wrapping external C libraries,
embedding CPython into existing applications, and for fast C modules that
speed up the execution of Python code.