Byte-compiled pyc files
Importing a module is a relatively costly affair, so Python does some tricks to make it faster. One way is to create byte-compiled files with the extension .pyc which is an intermediate form that Python transforms the program into (remember the introduction section on how Python works?). This .pyc file is useful when you import the module the next time from a different program - it will be much faster since a portion of the processing required in importing a module is already done. Also, these byte-compiled files are platform-independent.
- Note - These .pyc files are usually created in the same directory as the corresponding .py files. If Python does not have permission to write to files in that directory, then the .pyc files will not be created.