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Choosing a License
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.. image:: /_static/photos/33907149294_82d7535a6c_k_d.jpg

Your source publication *needs* a license. In the US, unless a license is
specified, users have no legal right to download, modify, or distribute the product.
Furthermore, people can't contribute to your code unless you tell them what
rules to play by. Choosing a license is complicated, so here are some pointers:

Open source. There are plenty of `open source licenses
<http://opensource.org/licenses/alphabetical>`_ available to choose
from.

In general, these licenses tend to fall into one of two categories:

1. licenses that focus more on the user's freedom to do with the
   software as they please (these are the more permissive open
   source licenses such as the MIT, BSD, and Apache)

2. licenses that focus more on making sure that the code itself —
   including any changes made to it and distributed along with it —
   always remains free (these are the less permissive free software
   licenses such as the GPL and LGPL)

The latter are less permissive in the sense that they don't permit
someone to add code to the software and distribute it without also
including the source code for their changes.

To help you choose one for your project, there's a `license chooser <http://choosealicense.com/>`_;
**use it**.

**More Permissive**

- PSFL (Python Software Foundation License) -- for contributing to Python itself
- MIT / BSD / ISC

  + MIT (X11)
  + New BSD
  + ISC

- Apache

**Less Permissive:**

- LGPL
- GPL

  + GPLv2
  + GPLv3

A good overview of licenses with explanations of what one can, cannot,
and must do using a particular software can be found at
`tl;drLegal <https://tldrlegal.com/>`_.
