${PYTHON}/Doc/glossary.rst bytecode Python source code is compiled into bytecode, the internal representation of a Python program in the interpreter. The bytecode is also cached in ``.pyc`` and ``.pyo`` files so that executing the same file is faster the second time (recompilation from source to bytecode can be avoided). This "intermediate language" is said to run on a :term:`virtual machine` that executes the machine code corresponding to each bytecode.