I found all the other modules in Python33/Lib, but I can't find these. I'm sure there are others "missing" too, but these are the only ones I've noticed. They work just fine when I import them, I just can't find them. I checked sys.path and they weren't anywhere in there. Are they built-in or something?
The math and sys modules are builtins -- for purposes of speed, they're written in C and are directly incorporated into the Python interpreter.
To get a full list of all builtins, you can run:
>>> import sys
>>> sys.builtin_module_names
On my machine, that results in the following list:
__builtin__
__main__
_ast
_bisect
_codecs
_codecs_cn
_codecs_hk
_codecs_iso2022
_codecs_jp
_codecs_kr
_codecs_tw
_collections
_csv
_functools
_heapq
_hotshot
_io
_json
_locale
_lsprof
_md5
_multibytecodec
_random
_sha
_sha256
_sha512
_sre
_struct
_subprocess
_symtable
_warnings
_weakref
_winreg
array
audioop
binascii
cPickle
cStringIO
cmath
datetime
errno
exceptions
future_builtins
gc
imageop
imp
itertools
marshal
math
mmap
msvcrt
nt
operator
parser
signal
strop
sys
thread
time
xxsubtype
zipimport
zlib
These modules are not written in Python but in C.
You can find them (at least on linux) in a subfolder of the lib-folder called lib-dynload.
The math module is then in a file math.cpython-33m.so (on windows probably with .dll instead of .so). The cpython-33m part is my python version (3.3).
The modules like math, time, gc are not written in python and as rightly said in above answers that they are somewhere (written or moduled) within python interpreter. If you import sys and then use sys.builtin_module_names (it gives tuple of module names built into this interpreter). math is one such module in this list. So, we can see that math comes from here and is not separately written in library or any other folder as a python code.
来源：https://stackoverflow.com/questions/18857355/where-are-math-py-and-sys-py