When you post a question or answer, you choose the license you are granting for the entire post. For example, the license granted on this post is CC0 1.0 as indicated above.
You can also, optionally, choose to grant an additional (dual) license for the portions of the post that are your own original source code. You should make it clear in your post exactly which code this refers to if there is any ambiguity.
The additional license is currently limited to this list, but we may add other licenses to the list if there is demand:
* [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0): CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
* [ALv2](https://www.apache.org/licenses/LICENSE-2.0): Apache License, Version 2.0
* [MIT](https://opensource.org/licenses/MIT): The MIT License
* [GPLv2](https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html): GNU General Public License, version 2
* [GPLv3](https://www.gnu.org/licenses/gpl-3.0.html): GNU General Public License
* [AGPLv3](https://www.gnu.org/licenses/agpl-3.0.html): GNU Affero General Public License
* [LPPL 1.3c](https://www.latex-project.org/lppl/lppl-1-3c): The LaTeX project public license (LPPL), version 1.3c