Whats the difference between a module and a library in Python?

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I have background in Java and I am new to Python. I want to make sure I understand correctly Python terminology before I go ahead.

My understanding of a module is: a script which can be imported by many scripts, to make reading easier. Just like in java you have a class, and that class can be imported by many other classes.

My understanding of a library is: A library contains many modules which are separated by its use.

My question is: Are libraries like packages, where you have a package e.g. called food, then:

  • chocolate.py
  • sweets.py
  • biscuts.py

are contained in the food package?

Or do libraries use packages, so if we had another package drink:

  • milk.py
  • juice.py

contained in the package. The library contains two packages?

Also, an application programming interface (API) usually contains a set of libraries is this at the top of the hierarchy:

  1. API
  2. Library
  3. Package
  4. Module
  5. Script

So an API will consist off all from 2-5?

From The Python Tutorial – Modules

  • Module:

    A module is a file containing Python definitions and statements. The file name is the module name with the suffix .py appended.

  • Package:

    Packages are a way of structuring Python’s module namespace by using “dotted module names”.

If you read the documentation for the import statement gives more details, for example:

Python has only one type of module object, and all modules are of this
type, regardless of whether the module is implemented in Python, C, or
something else. To help organize modules and provide a naming
hierarchy, Python has a concept of packages.

You can think of packages as the directories on a file system and
modules as files within directories, but don’t take this analogy too
literally since packages and modules need not originate from the file
system. For the purposes of this documentation, we’ll use this
convenient analogy of directories and files. Like file system
directories, packages are organized hierarchically, and packages may
themselves contain subpackages, as well as regular modules.

It’s important to keep in mind that all packages are modules, but not
all modules are packages. Or put another way, packages are just a
special kind of module. Specifically, any module that contains a
__path__ attribute is considered a package.

Hence the term module refers to a specific entity: it’s a class whose instances are the module objects you use in python programs. It is also used, by analogy, to refer to the file in the file system from which these instances “are created”.

The term script is used to refer to a module whose aim is to be executed. It has the same meaning as “program” or “application”, but it is usually used to describe simple and small programs(i.e. a single file with at most some hundreds of lines). Writing a script takes minutes or few hours.

The term library is simply a generic term for a bunch of code that was designed with the aim of being usable by many applications. It provides some generic functionality that can be used by specific applications.

When a module/package/something else is “published” people often refer to it as a library. Often libraries contain a package or multiple related packages, but it could be even a single module.

Libraries usually do not provide any specific functionality, i.e. you cannot “run a library”.

The API can have different meanings depending on the context. For example:

  • it can define a protocol like the DB API or the buffer protocol.
  • it can define how to interact with an application(e.g. the Python/C API)
  • when related to a library/package it simply the interface provided by that library for its functionality(set of functions/classes/constants etc.)

In any case an API is not python code. It’s a description which may be more or less formal.

Only package and module have a well-defined meaning specific to Python.

  1. An API is not a collection of code per se – it is more like a “protocol” specification how various parts (usually libraries) communicate with each other. There are a few notable “standard” APIs in python. E.g. the DB API

  2. In my opinion, a library is anything that is not an application – in python, a library is a module – usually with submodules. The scope of a library is quite variable – for example the python standard library is vast (with quite a few submodules) while there are lots of single purpose libraries in the PyPi, e.g. a backport of collections.OrderedDict for py < 2.7

  3. A package is a collection of python modules under a common namespace. In practice one is created by placing multiple python modules in a directory with a special __init__.py module (file).

  4. A module is a single file of python code that is meant to be imported. This is a bit of a simplification since in practice quite a few modules detect when they are run as script and do something special in that case.

  5. A script is a single file of python code that is meant to be executed as the ‘main’ program.

  6. If you have a set of code that spans multiple files, you probably have an application instead of script.

Library : It is a collection of modules.

(Library either contains built in modules(written in C) + modules written in python).

Module : Each of a set of standardized parts or independent units that can be used to construct a more complex structure.

Speaking in informal language, A module is set of lines of code which are used for a specific purpose and can be used in other programs as it is , to avoid DRY(Don’t Repeat Yourself) as a team and focusing on main requirement. source

API is an interface for other applications to interact with your library without having direct access.

Package is basically a directory with files.

Script means series of commands within a single file.

I will try to answer this without using terms the earliest of beginners would use,and explain why or how they used differently, along with the most “official” and/or most understood or uniform use of the terms.

It can be confusing, and I confused myself thinking to hard, so don’t think to much about it. Anyways context matters, greatly.

Library– Most often will refer to the general library or another collection created with a similar format and use. The General Library is the sum of ‘standard’, popular and widely used Modules, witch can be thought of as single file tools, for now or short cuts making things possible or faster. The general library is an option most people enable when installing Python. Because it has this name “Python General Library” it is used often with similar structure, and ideas. Witch is simply to have a bunch of Modules, maybe even packages grouped together, usually in a list. The list is usually to download them. Generally it is just related files, with similar interests. That is the easiest way to describe it.

Module– A Module refers to a file. The file has script ‘in it’ and the name of the file is the name of the module, Python files end with .py. All the file contains is code that ran together makes something happen, by using functions, strings ect.
Main modules you probably see most often are popular because they are special modules that can get info from other files/modules.
It is confusing because the name of the file and module are equal and just drop the .py. Really it’s just code you can use as a shortcut written by somebody to make something easier or possible.

Package– This is a termis used to generally sometimes, although context makes a difference. The most common use from my experience is multiple modules (or files) that are grouped together. Why they are grouped together can be for a few reasons, that is when context matters.
These are ways I have noticed the term package(s) used. They are a group of Downloaded, created and/or stored modules. Which can all be true, or only 1, but really it is just a file that references other files, that need to be in the correct structure or format, and that entire sum is the package itself, installed or may have been included in the python general library. A package can contain modules(.py files) because they depend on each other and sometimes may not work correctly, or at all. There is always a common goal of every part (module/file) of a package, and the total sum of all of the parts is the package itself.

Most often in Python Packages are Modules, because the package name is the name of the module that is used to connect all the pieces. So you can input a package because it is a module, also allows it to call upon other modules, that are not packages because they only perform a certain function, or task don’t involve other files. Packages have a goal, and each module works together to achieve that final goal.

Most confusion come from a simple file file name or prefix to a file, used as the module name then again the package name.

Remember Modules and Packages can be installed. Library is usually a generic term for listing, or formatting a group of modules and packages. Much like Pythons general library. A hierarchy would not work, APIs do not belong really, and if you did they could be anywhere and every ware involving Script, Module, and Packages, the worl library being such a general word, easily applied to many things, also makes API able to sit above or below that. Some Modules can be based off of other code, and that is the only time I think it would relate to a pure Python related discussion.


The answers/resolutions are collected from stackoverflow, are licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0 .

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