Base language of Python

The sources are public. Python is written in C (actually the default implementation is called CPython).

You can't say that Python is written in some programming language, since Python as a language is just a set of rules (like syntax rules, or descriptions of standard functionality). So we might say, that it is written in English :). However, mentioned rules can be implemented in some programming language. Hence, if you send a string like 'import this' to that program called interpreter, it'd return you "Zen of Python".

Since most modern OS are written in C, compilers/interpreters for modern high-level languages are also written in C. Python is not an exception - its most popular/"traditional" implementation is called CPython and is written in C.

There are other implementations:

• IronPython (Python running on .NET)
• Jython (Python running on the Java Virtual Machine)
• PyPy (A fast python implementation with a JIT compiler)
• Stackless Python (Branch of CPython supporting microthreads)