It's common in source-code to place a so called license-plate on top of each file. Those tell typically:

1. Of which program that file is part of.
2. The copyright holder and date (and how to contact, e.g. email).
3. The license terms, either abbreviated (and referenced) or in full.

If you open your source-code repository to the public, this (per-file) method ensures that your copyright and licensing terms are visible before someone modifying the file.

It's normally best to choose an established license so actually users reading the code understand the licensing terms. But the choice of the license is fore-most entirely your business.

Some source-code repositories do only allow some of the known licenses however, namely any OSI approved license for google project hosting.

You might want to make use of copyleft for your code. Copyleft ensures that the freedom you give with your software will be preserved for future users because they are reciprocal, users of your code need to distribute the code under the same license.

Copyleft licenses for code are the GNU GPL or LGPL. The GPL is most famously used by software authors across the globe to preserve software freedom. But that's your decision, the GNU website has more information about licenses and licensing that might be helpful.

Non-reciprocal licenses often do not require to pass on changes under the same license / in source-code form. Examples of those are Apache 2.0 or BSD two clause. Some users prefer these licenses because they want that their code can be incorporated into non-free works.

So it's basically your decision under which terms you want to publish your code and how much control you want to give your users.

It's common in source-code to place a so called license-plate on top of each file. Those tell typically:

1. Of which program that file is part of.
2. The copyright holder and date (and how to contact, e.g. email).
3. The license terms, either abbreviated (and referenced) or in full.

If you open your source-code repository to the public, this (per-file) method ensures that your copyright and licensing terms are visible before someone modifying the file.

It's normally best to choose an established license so actually users reading the code understand the licensing terms. But the choice of the license is fore-most entirely your business.

Some source-code repositories do only allow some of the known licenses however, namely any OSI approved license for google project hosting.

You might want to make use of copyleft for your code. Copyleft ensures that the freedom you give with your software will be preserved for future users because they are reciprocal, users of your code need to distribute the code under the same license.

Copyleft licenses for code are the GNU GPL or LGPL. The GPL is most famously used by software authors across the globe to preserve software freedom. But that's your decision, the GNU website has more information about licenses and licensing that might be helpful.

Non-reciprocal licenses often do not require to pass on changes under the same license / in source-code form. Examples of those are Apache 2.0 or BSD Two Clause. Some users prefer these licenses because they want that their code can be incorporated into non-free works.

So it's basically your decision under which terms you want to publish your code and how much control you want to give your users.

A personal note:

For projects I don't know where they head to, I often choose the GNU GPL because this will keep things open for the future publicly. And it makes it harder for others to snap the project and build something on top of it keeping me out. That's especially true if your code is not that advanced that users actually need you to modify it because of your expertise.

It's common in source-code to place a so called license-plate on top of each file. Those tell typically:

1. Of which program that file is part of.
2. The copyright holder and date (and how to contact, e.g. email).
3. The license terms, either abbreviated (and referenced) or in full.

If you open your source-code repository to the public, this (per-file) method ensures that your copyright and licensing terms are visible before someone modifying the file.

It's normally best to choose an established license so actually users reading the code actually understand the licensing terms. But the choice of the license is fore-most entirely your business.

Some source-code repositories do only allow some of the known licenses however, namely any OSI approved license.

You might want to make use of copyleft for your code. Copyleft ensures that the freedom you give with your software will be preserved for future users because they are reciprocal, users of your code need to distribute the code under the same license.

Copyleft licenses for code are the GNU GPL or LGPL. The GPL is most famously used by software authors across the globe to preserve software freedom. But that's your decision, the GNU website has more information about licenses and licensing that might be helpful.

It's common in source-code to place a so called license-plate on top of each file. Those tell typically:

1. Of which program that file is part of.
2. The copyright holder and date (and how to contact, e.g. email).
3. The license terms, either abbreviated (and referenced) or in full.

If you open your source-code repository to the public, this (per-file) method ensures that your copyright and licensing terms are visible before someone modifying the file.

It's normally best to choose an established license so actually users reading the code understand the licensing terms. But the choice of the license is fore-most entirely your business.

Some source-code repositories do only allow some of the known licenses however, namely any OSI approved license for google project hosting.

You might want to make use of copyleft for your code. Copyleft ensures that the freedom you give with your software will be preserved for future users because they are reciprocal, users of your code need to distribute the code under the same license.

Copyleft licenses for code are the GNU GPL or LGPL. The GPL is most famously used by software authors across the globe to preserve software freedom. But that's your decision, the GNU website has more information about licenses and licensing that might be helpful.

Non-reciprocal licenses often do not require to pass on changes under the same license / in source-code form. Examples of those are Apache 2.0 or BSD two clause. Some users prefer these licenses because they want that their code can be incorporated into non-free works.

So it's basically your decision under which terms you want to publish your code and how much control you want to give your users.