Python ‐ a tool, not a reptile - zamaniamin/python GitHub Wiki
What is Python?
Python is a widely-used, interpreted, object-oriented, and high-level programming language with dynamic semantics, used for general-purpose programming.
And while you may know the python as a large snake, the name of the Python programming language comes from an old BBC television comedy sketch series called Monty Python's Flying Circus.
Python rivals?
Python has two direct competitors, with comparable properties and predispositions. These are:
Perl– a scripting language originally authored by Larry Wall;Ruby– a scripting language originally authored by Yukihiro Matsumoto.
There is more than one Python
There are two main kinds of Python, called Python 2 and Python 3.
These two versions of Python aren't compatible with each other. Python 2 scripts won't run in a Python 3 environment and vice versa, so if you want the old Python 2 code to be run by a Python 3 interpreter, the only possible solution is to rewrite it, not from scratch, of course, as large parts of the code may remain untouched, but you do have to revise all the code to find all possible incompatibilities. Unfortunately, this process cannot be fully automatized.
It's too hard, too time-consuming, too expensive, and too risky to migrate an old Python 2 application to a new platform, and it's even possible that rewriting the code will introduce new bugs into it. It's easier, and more sensible, to leave these systems alone and to improve the existing interpreter, instead of trying to work inside the already functioning source code.
Python aka CPython
First of all, there are the Pythons which are maintained by the people gathered around the PSF (Python Software Foundation), a community that aims to develop, improve, expand, and popularize Python and its environment. The PSF's president is Guido von Rossum himself, and for this reason, these Pythons are called canonical. They are also considered to be reference Pythons, as any other implementation of the language should follow all standards established by the PSF.
Guido van Rossum used the "C" programming language to implement the very first version of his language and this decision is still in force. All Pythons coming from the PSF are written in the "C" language. There are many reasons for this approach. One of them (probably the most important) is that thanks to it, Python may be easily ported and migrated to all platforms with the ability to compile and run "C" language programs (virtually all platforms have this feature, which opens up many expansion opportunities for Python).
This is why the PSF implementation is often referred to as CPython. This is the most influential Python among all the Pythons in the world.
Cython
Another Python family member is Cython.
Cython is one of a possible number of solutions to the most painful of Python's traits – the lack of efficiency. Large and complex mathematical calculations may be easily coded in Python (much easier than in "C" or any other traditional language), but the resulting code execution may be extremely time-consuming.
How are these two contradictions reconciled? One solution is to write your mathematical ideas using Python, and when you're absolutely sure that your code is correct and produces valid results, you can translate it into "C". Certainly, "C" will run much faster than pure Python.
This is what Cython is intended to do – to automatically translate the Python code (clean and clear, but not too swift) into "C" code (complicated and talkative, but agile).
Jython, PyPy, and RPython, there are another version of Python!
source: Python Institute