Modules are collections of Python code that are bundled together in a common namespace, and which are brought into the Python interpreter via the import keyword. Modules can include class and function definitions, data, and executable Python code. Much of the functionality that the Python ecosystem offers is not built-in by default in the interpreter, but can be imported from either the Python Standard Library or from the huge collection of third-party packages available online. The terms "module", "package", and "library" are sometimes used interchangeably, but module is actually the type of the Python object representing the collective namespace and its contents that are imported.